Newman cams all look to have really low lift from that chart so i wouldnt expect thats happened here, Unless.... look closely for marks or shiny spots on the other pistons in the exhaust valve pockets and if there are then my money would be on the oem valve springs are too light and they were hitting pistons at high revs
heres a thread to the new 3.0 race build lots of info
http://www.e30tech.com/forum/showthread.php?t=117701
nice tidy job on the valve, it only hit the piston about 3 times and left a couple little niks in it.
