Hello everyone. This is my first chevy build and I need your help. I am building 454 for my 70 Stepside. The engine casting number is 3999289. The casting number on the heads is 353049. I would like 400 to 500hp.
I bought a edelbrock Airgap intake so far and that is it. I am in the process of taking the engine apart so I can head to the machine shop! I need help with camshaft etc... What do I need to do with the heads...

353049 heads were used on 1970-1973 light trucks with either a engine designation of 400 or 402. In reality they are exactly the same. Gm tried for a short while to market your choice of a 400 small block or a 400 big block in thier cars and trucks. These heads were also used on 1973-1976 Trucks, passenger cars, chevelle, and corvette. They are oval port heads likely with the small valves. They are great on street engines. Rpm quickly. Have great torque. They do have a rpm limit though as you get into the upper rpm's they tend to loose a bit. (Especially on larger displacement engines 482 cid or more above 6000-6500 rpm) I do not see any reason why you could'nt get 1 hp per cid with oval port heads. Gasket match intake and exhaust. Good quailty 3 angle valve job,guides replaced if needed. ( I suggest bronze). The block 399289 was used in 1972 454 corvette(270hp), 1972-1975 454 Chevelle,1972-1976 454 passenger cars in general,and 1973-1979 454 trucks. Good block. Generally have plenty of material for over bore. Likely a 2 bolt main which should not be a problem for the 400-500 hp level your looking at. Camshaft wise you won't need anything real wild or radical. There are some on here with MUCH more camshaft know how than I have. Anybody else help him out?

Search 'Low Buck 454' or threads stating '454' over the last few weeks.
At least 2 here per week....plenty of info!
You'd have to try pretty hard NOT to get 450 hp and 500 ft lbs with a mild engine!
You starting out with a 454 and 049 heads is a huge plus!