Bronze and stainless (316)

Bronze and SS are really close on the galvanic scale, it should be ok.

Don't do it. Can't mix bronze and stainless together.

Know your Underwater Alloys | Steve D'Antonio Marine Consulting (stevedmarineconsulting.com)

Here's another great article on it:
"Stainless steel’s other primary weakness, the aforementioned crevice or pitting corrosion (there is a scientific distinction between the two, however, for the purposes of this discussion it’s not relevant), occurs when it is used in an oxygen depleted environment. The tough, nearly impenetrable oxide film that forms as soon as stainless steel is exposed to air (the term inox, seen on many European stainless components, is simply an abbreviation for inoxodizable, which refers to stainless steel’s resistance to oxidization or staining) only remains intact as long as the metal is exposed to oxygen. If stainless steel is placed in an environment where it is starved of oxygen and it is exposed to water, either fresh or salt, it becomes susceptible to crevice corrosion, which typically manifests itself as roughness, valleys, pitting, or even worm-like holes.

The most likely location for crevice corrosion to occur is when stainless alloys are used for raw-water and underwater hardware, which may include propeller shafts, struts, raw-water intake and discharge plumbing, exhaust systems, shaft logs and fasteners, or nuts, bolts, and screws that are used below the waterline to secure hardware such as struts, seacocks, hull strainers, swim platform supports, etc. Because nearly all commonly available fasteners are made of 304 alloy, they run an exceptionally high risk of suffering from crevice corrosion when used in below-the-waterline applications (they are particularly prone to corrosion where they cannot be easily inspected, as they pass through the hull for instance). And, the exposure to water does not necessarily require submergence, stainless steel that is imbedded in hydroscopic materials such as wood, foam core, or even fiberglass may suffer from crevice corrosion.

Therefore, it is preferable to avoid using stainless steel in applications where it is regularly exposed to stagnant or still water for extended periods. Ideally, high-quality silicon bronze, cupronickel, Inconel, or non-metallic alternatives should be used, particularly for fasteners and raw-water plumbing. The fasteners used to secure struts, strainers, and other underwater hardware, for instance, should be bronze rather than stainless steel. If stainless steel must be used in such an application, for a custom-made strut or shaft log for instance, it should be fabricated from the most corrosion resistant marine alloy available, 316L or 317L.

Propeller shafts fall into a special category. Because they require both exceptional strength and corrosion resistance, propeller shafts are typically fabricated from a proprietary stainless alloy that includes a host of other trace elements. These mixtures yield the ideal combination for the environment in which shafts operate. Trade names such as Aquamet, Aquatech, and Aqualoy, among others, are available in several strength and corrosion resistance grades, the most corrosion-resistant of which, and therefore desirable for recreational applications where use and oxygen exposure is limited, is designated as 22. Shafts made of this alloy and grade are as close as a boatbuilder can get to corrosion-proof where steel-based alloys are concerned."
Stainless Steel and Corrosion - PassageMaker

Keep TefGel or Teflon tape down to a minimum.
Rather, a conducting grease on most of the threads.
If the Bronze and Stainless are in good electrical contact with other, there should be minimum stray currents flowing thru any electrolyte between them.
This will help reduce the galvanic erosion down.
The grease will also keep the black or crevice corrosion down on the stainless parts.
All above is a poker hand (fair) that does not really have to be played.

If it was my boat, I'd keep it all bronze.
I have slept well aboard now for 17 years.

Nothing beats Bronze in salt water.

I can't answer that, but in all my years and thousands and thousands of yachts that I've stepped foot on, I've never once seen a S/S sea strainer body.

Nor a stainless raw water pump. I don't understand the potential stainless market Groco sees for that strainer, but I wouldn't do it.

Although it is not stated, maybe those Groco SS strainers or mostly intended for fresh water?
I agree with others, bronze all the way. All the ships I work on, all the strainers (huge ones) are bronze. Occasionally we see monel, but never stainless.

Twice? You're lucky. I have a bucket full of the wrong sizes of most everything two or three times. But, yes, don't second guess yourself or the experience posted here by folks that know more than I do as well. Go bronze and don't need to look back. No need to build your own batteries.

Your head ache is for a reason; Nobody wants to trust pipe connected to pipe making hard mechanical contraptions.
These things fail quickly on a boat full of vibrations, harmonics and velocities in every direction.
Hose is better than pipe.
Bronze hose barbs and hose with the best clamps in town.
Yes, When you want to screw that gizmo directly to that thingie, you look for a nipple or pipe.
And Marlon won't carry the weight. You replace pipe with hose.

You can try and call, not web search, folks like McMaster-Carr or Jamestown to find some old salt behind the counter.
They can offer nipples in bronze but I would recommend (& they may also) to stay away from large assemblies built this way.
Walk quickly (very quickly) away from some kid that starts talking about red brass.

Your opening picture did scare the hell out of me.