Zip,Somehow I got the idea Your 434 was going to be 18 deg.Senoir moment I guess.You would need a pretty good 18 head to be 60 cfm better than the heads you have,I think.But you could probably do one for the same money as any small block that needs shaft rockers.I did An 18 for my car last year 412 inch 4.155x3.800 6.125 rod&434 pistons.83 Camaro stock body with cage,stock suspension 3400 lbs with me,best 60-1.36 1/8-6.23/110 1/4 9.81/138. 10 in.slick open ex. Still tunning Bill.