390 stroker ?

450 hp from a small block stroker is no problem, just put a decent set of heads on it.

My 410 (360) stroker has a small solid roller cam, 10.8:1 compression, ported Edelbrock heads, a little 750 carb, and runs on 93 octane pump gas. It makes about 530 hp, very street friendly and in street trim (through the mufflers) runs 6.8's @ 99mph in the 1/8 mile.

The same combo on a 318 block would run close to the same.