Thanks much for all the good input!

I did measure using clay. I use a composition head gasket. The heads have the regular valve springs on them; didn't have a set of lightweight springs for this purpose.

I didn't measure at zero lash. I'd set valve lash per cam mfr's info. There was plenty of clearance on the exhaust side.

This used to be a 4 speed car, and 7000 RPM was not unheard of. It's now an automatic and I've switched a number of other things to try and avoid twisting it that hard.

Having said all that, I'd not thought of retarding the cam. That would seem a good option at this point, particularly since I appear to be flush with clearance on the exhaust side. Been too many years. I'll pursue that and recheck.

Cab, I will check all cylinders. Your point on rod length was another one I'd not considered.

Thank you again guys for all your wisdom! It's great to be able to come on here and run this sort of stuff by you all.