My girlfriend's dad has an injected 454 that is bored out to 510 that he runs in his 69 SS 396 street/strip chevelle, Of course its built to run 9's in the 1/4, don't know if you want that kind of power or what...

I think i'd probably choose the 383 just because it gives you a good amount of power and you wouldn't be measuring your milage in GALLONS TO MILES while your out cruising.

Just my 2 cents.

However, you can never go wrong with a good sturdy built 350.