We beat a 400 small block Chevy without mercy for 18 years in a 18 ft. Horizon.  Not a daycruiser by any stretch but more fun than any neighborhood should be allowed to have.  First a 350 w/ a Z/28 crossram and single four for a few years then built a 400 sm.blk just because.  Burned a ton of fuel due to ungodly hours towing and skiing for a decade or two.  That motor got fantastic mileage and we would still go thru 100 gal. of gas on some weekends. 
I say go for it but I'm just biased I guess.