Congratulations on fooling yourself into believing you will EVER really be done !
I have 410 Hp, 671's with turbos.
They are rated at 2650 rpm no load and 2550 at full load.
I run mine at 2250.
Depending on the wind and the tides and the sun and the moon, I run at anywhere between 20 and 22 knots@2250.
At 2100 rpm I run around 19, 20 knots
I burn about 25 gals per hour consistantly.
My starboard tank always takes about 20 gallons more than my port tank which I attribute to the genny.
I generally do not let the tanks get less than 1/2 full and more than likely top off after any long distance travel because I like the boat heavey in case of rough seas. This is my own opinion.
I run the genny whenever I run the boat to keep it limber. ( 7.5 Kw Onan )
At 17 knots and below the boat does not respond well.
It is on plane but seems almost in transition, it wallows in a sea.
3.5 feet draft is the same as mine.
48000 Lbs is what I always quoted lift operators but I do not think it ever tipped the scales on those same lifts at that much.
I never wrote it down but I think the most she ever weighed on a lift was 42000 lbs. that was full of fuel but no water at all.
I only have 80 gallons water storage after removeing the original tanks that had split and replacing them with bladder type tanks.
This is adequate for my use around the bay.
Also mine is the galley down model which has a rinky dinky sized dinnette and long isle style galley.
The salon is pretty big and comfortable.
This boat layout is perfect for two of us.
I wish you the best with you Post.
I have enjoyed the heck outta mine.
Where will you keep the boat ?