Mercruiser 482 high performance
 

Hi,
I'm new to the forum after just picking up a 1970 35' Magnum Sport Fisherman. It's powered by twin 482 Tall block Mercruisers with o ringed heads. I'm still in the restoration process so haven't had the boat out yet. Engines seem fine with relatively low hrs. I am expecting that once I get her going I'll get around .5 nmpg. Is this accurate?
Is it advised to repower with diesels, and if so, is the a market for my current engines?