I've got a 400HP 350 that uses ported 305 heads and 11.7:1 compression. I only got about 203 cfm after porting and only 1.84 valves, so I'm looking for less restricting heads. I want to keep the high compression so I want the same 58cc chamber size, and I also want to do some more porting for experience. I happened to come across some L98 corvette heads on ebay and they have the 58cc chambers, however they are selling for $400 US. Is it worth me to port these heads heavily with bigger valves or are they a poor casting? $400 is a lot to start with if I still have to invest in building them.