roller rockers

fishy68 said
That's what my machinist tells me too. He runs his 340 up to 7,000 rpm and runs mid 10's with it with the stock ductile rockers.

I have a set of bushed MP ductile arms on my W2s and have run them just past 6500 (which is the range they are advertised for). The unbushed versions are supposed to be good up to 6K.