Stage 1. If you are looking for some more HP, go to a cam, lifters and timing chain. I just put in a CompCam High Energy cam, timing chain, lifters and spring kit and I liked the response. Use that old HEI ignition too with new cap, rotor, wires and plugs. Don't spend too much money on plugs. Use original numbers that came with that engine.
Stage 2. If you want to spend more, go with an intake manifold. An Edelbrock RPM, or a WEIAND Stealth would be good.
If you have a "good" Quadreajet...keep it. Otherwise, try a 600 CFM carb. If you go too much bigger you will loose low end performance.
Any stage. If you want to really help what you have in all areas, put in a dual exhaust with a crossover pipe. Headers would be an addition, but they will create more noise (sound) inside too. At any stage, dual exhaust will sound good. It will make you think its hot even if it is not.
If you are going to pull the oil pan off, Might as well check the main bearings and rod bearings too.
If you are going that far, you might as well at least re-ring it and break the cylinder glaze.
If you pull the heads, might as well lap the valves and put in new valve seals. They would come with a cam, lifters, springs and timing chain kit.
Get a couple of cans of chevy orange engine paint too. You are going to want it to look good.
That is the order I would choose to do things if I could only do one or two. An exhaust will sound and perform good at any point though. The most immediate HP will be with the cam kit.
You could also put on some iron vortec heads and intake. That can be a 20-40hp gain. I could spend your money all day too. Maybe you just want a good tuneup and oil change. lol
Good luck!
