See my sig. I have well under $3000 into it using a new carb-used will save you some $$, and it dyno'ed 400.1hp even with the crappy carb.
You can start with a core engine like me (mine also needed a reground crank and resized rod, which added to my bill). It was 19,000 miles, so cylinder walls were good. Heads had minor clean-up porting done, screw-in ARP studs, and spring pockets machined for GM's HOT cam kit springs. Had bigger valves put in, good valve job done. Other than that, it's all basic stuff. Gasket set was from Northern Auto Parts in Iowa, they're pretty cheap and you can customize the rebuild kit with upgraded rings, bearings, oil pump, etc. Prices have also gone down on the intake since I did mine a few years ago.