Getting the most out of a low comp 440

Has a '68 318 and 727, unknown mileage. 9mpg if I drive it hard, 11easy driving. Leaks and smokes, but it runs. Doesn't make much power, but the power curve feels good for what it is. Pulls from the bottom up to 4500.

I like to rev stuff a bit...what's a stock 440 bottom end good for?

Probably 6500 with the right cam, lifters and springs.