I have a set of C5AE heads that I wanted to do the late model rocker arm swap that has been discussed recently. I had the heads cleaned and checked first, tried my hand at porting them, and after reading some posts on folks having troubles with the original rocker arm usage, I thought this looked like something pretty cool to do! Several of the original push in studs had cuts in the side of them from the rocker arms biting into them-same on my hipo studs when I had those heads rebuilt... I have the rockers and bolt down fulcrums off some E7FE heads-they have the bolt thru style fulcrum which apparently will work if you can't find the old boss 302 style fulcrum...I also have a set of new 3/8 style screw in studs to use as well vs the 7/16 boss 302 larger ones...So my questions are how much of the square pedestal needs cut off the bottom of these fulcrums, and can I just drill out the fulcrum using a 3/8 drill bit? I was going to have the machine shop tap the heads for the screw in studs, and I am sure they could modify the fulcrums as well, but if I can do them I will. I also was going with hardened exhaust seats and 351W valves and new guides and vitron style seals-Any preference for iron over bronze style valve guides? I know alum heads are better, easier, cheaper etc...but I am enjoying the work on these old original heads for the 65 I have all apart.