rtc-8

I just got a new predator motor (non hemi) to replace an old one. The old one has a RTC-2 marked head and the new one has a RTC-8 marked head. Would the RTC-2 be any better than the 8? We plan to add 18# springs and a mild cam, header and cone filter. Just wondering if any gains would be made...

Im currently building a radical predator engine. I have pretty aggressively ported RTC-8 head. I was wondering if anyone made some stainless steel valves with the 5mm valve stems. If not how can I make some fit. I was thinking of drilling out the valve stems on a drill press but i don't know if...