When I rebuilt my V8 I used a Holley with a secondary metering kit mated to an offi manifold also used a Piper fast road cam and various other mods which cost me over 2.5K and that was for the bits with me doing the work.
If your not going to throw money at it then tbh just make it breathe better, tune up, decent filtration and better exhaust. The most noticable mod was when I fitted a lightened/balanced flywheel, engine spun up much quicker.