would it be a waste to put a set of afr or tw on a stock bottom end? I have a cobra intake bbk air intake and exhaust. I gueass i would need a new cam too
Absolutely not. Thats what the aftermarket is for Not only will you notice large SOTP differances but if you ever do go with an aftermarket block you can always transfer it over...hence 'bolt on'. I've got ported GT40's on my stock bottom and its fantastic. Just dont go too big. AFR 185's are plenty big and would work with a aftermarket block later. Although the 165's would be a better choice if you plan on sticking with the stock block.
If you go with heads that keep the stock valve angle (nearly all the aftermarket bolt-on heads except the TFS Twisted Wedge) remember to use no larger than a 1.90" intake valve. The 2.02" intake valves usually require notching the stock pistons. The AFR 185's all come with 2.02's and the 165's come w/ 1.90" valves.