I have located a 1973 41' Seacrest That was re powered with twin diesels (100 HP Iveco Marine Diesels). This boat size, layout, and amenities better meet what we have talked about in looking for our "forever boat" (if there is such a thing)

I am looking for input from folks on here who may have experience operating a Seacrest Houseboat Hull. In looking at the pictures of the houseboats the hull really does not look that different then the cruisers/sedans. There is actually substantially more of a 'flare' at the top that would seem to catch/divert spray when in rougher water possibly?? Has anyone operated a Marinette houseboat in rougher waters? Ie. The great lakes. Supposedly this vessel that I have my eyes on originally was owned and operated in the Virginia/Chesapeake Bay area.
We are definately needing a boat that will handle some rougher waters (2'-3' seas regularly with the potential for 4' or more occasionally). Thoughts?
I would have to believe that with the twin 100 HP diesels I could potentially double my fuel mileage at lower speeds/rpms. I don't need to cruise fast.
Anyone with first hand experience with these boats that can chime in would be greatly appreciated! Thanks