I figure you've got a couple options...
Heads, rockers, cam, better intake, headers, electronic ignition... with this option you've got quite a bit of disassembly and reassembly to do, and you'll probably have to buy a few little extras to make everything work (i.e. new head bolts, fuel line, pushrods, etc.) and you'll be into it for probably right around $2500 in parts alone.
A second option would to be a supercharger, like a Paxton unit. Kits are around $2500 to start and pretty much bolt on without a lot of disassembly (especially no disassembly of the long block), but then you'll probably also need to buy some extra bits (fuel line, fuel pump, fuel regulator, etc.), but you could also have it done in a weekend (maybe even just a Saturday if you're serious about it). I guess this one really depends on whether you want a supercharger under your hood... (I think they look cool, but it is one more thing under there and they do add weight).
Ultimately, either way you go you'll need to make sure you get the thing tuned well (maybe professionally) to get the numbers you're looking for.
Hope this helps...