Post 46 6-92 550 HP Performance ?

What color was the exhaust? Both mains WOT @ 2196?
TI & TIBs WOT should see 2250 rpm medium load. Some drivers believe in a bit more pitch (loss of WOT) for better cruise efficiency.
I guess it's up to you. If you're doing fair weather cruising, you're close to good. If you're planning on a lot of offshore runs and fishing, find that rpm. You will need it loaded and climbing over swells.

You will need base line maintenance. Including governor & rack adjustments. Test rpm and performance again and log it with your base line data; part numbers, work performed and hours.

Oh, were the tachs checked?

If you'r no load high idle was close to 2275, you're so close (assuming 2250 max loaded rpm).
I believe your close and not worry about messing with the wheels for now. Soon, your going to want the props checked within a base line maintenance work up. If your spinning 2245 and the other needs a rack checked out, you may find the missing 55 rpm. Fuel filters, old fuel, ding'd wheel, saturated air filter (may be) and others can lose 55 rpm. As long as you did not see any black or heavy grey smoke, your close.
The next important thing is your mechanic; Faith and confidence. Detroits have only been around for 80 years but only a few people can really understand and work on them. I have stories.

Skippy J and some other DD tech's can come in any time but I think you're close to a deal.

I think you're close enough in RPM's that it's not an issue to worry about whether you should buy the boat or not. I would do a tune-up on both engines (adjust the valves, set the rack/injectors), new fuel filters, clean air filters, and oil changes. Inspect turbo's if you can. At this point I would make sure the bottom is clean and run it. You can get a photo tach for $100 or less these days and just check them both at the crank and see what rpm's your getting. Then I would later do it with personal gear, full fuel/water etc. If at this point you're 100rpms or so down, I would cut the props. 50 rpm's I wouldn't worry about, however if you do get the chance at a later date I'd remove pitch. I'd rather see 50 rpms over than under. I also wouldn't worry about running them 1900-1950 either. Who marinized the engines? JT?