E tecs are much more efficient at low rpm than 4 strokes. Carb`d smokers? Yeah, they suck fuel at low rpms. Lots.
E tecs are DI.
Brian, a Mike Wilson recently came by our shop. His SUV had a 7 marine sticker on the rear window. He said Monty Racing was making E tecs outta old V8 300 Rude blocks. Said they take 2 fuel rails from the v6 motahs, cut and weld them for v8`s and are making north of 500 @ the prop.
Mike said Yamaha has offered Gordon boat loads of cash for his technology. Monty racing is the go to shop for Rude racers. He can build for longevity as well.
http://www.montyracing.com/index.html
I think you may be a little heavy for a single 300. Send your queery a little south maybe.
The old 21 ran with Homelite 4 strokes. 55 Bearcats. Based off of the Crosley modular design.
You may be suprized by that torque. Mr. Denny`s 150 jumps out of the hole. And I do mean hang on.
Cheers,
Us chickens