If your looking at new heads than pretty much anything will make more top end. It is hard to beat the low RPM power of the vortecs though. Your best bet would be to keep the vortecs and have them milled to raise compression a little. If I was to step up and wanted more power I would look at the chevy small port vortecs. There a little larger runners, larger valves, thicker deck, have screw in studs and handle more lift out of the box with out being too large of a runner for a street motor. If you want more power I would use these but would also use a slightly larger cam with them to get the most out of the swap and if your looking to just build a bad street motor and are not too worried about loosing a little low RPM torque I would get these heads, RPM air gap intake, 750 DP and a cam with about 220/230 duration @0.050 and run a 2,500 RPM stall but you would never want to tow with it again but would put you around 400HP or so. Just be good for street light runs and mud drags. I think some one on here recommended a big block to. I just picked up a good 454 for $700 that ran its whole life on propane and has never been rebuilt for my next build. Even with stock heads getting 400Hp and 500FTlb or torque is like falling off a log. For the price of new heads you could almost get a running 454 and have it in the truck. A 400 HP 454 would be very street friendly and have torque for days. Pretty much just need a cam swap and a few bolt on to get there.