8.1 Vortec 496 Gas Or 5.9 Cummins Diesel For A 1983 C20 4 Door Dually With A Turbo 400 3 Speed Auto

[Hugeroost]

I would rebuild the BB you already have, 30 over, intake carb LT headers a good cam and heads. You'd easily see 500hp at the flywheel or more, and if done right you be good for another 200k easy. So easy to make big power w those old 454's