Thank you for the comment! Always valuable input here.
Rocky I will definitely look at those rockers. That's what I want is improved function, with reliability. I think I breezed past those for some reason in the past. They look like a great option...especially since you've been running them since 2014! I want to have the confidence of jumping in the car, driving for 500 miles and not get stuck somewhere.
Mr. Bosswrench! I can always count on your great info! I never thought about a machinist screwing up a head when machining the pedestals to accept a 7/16 stud! Fortunately, I do have three sets of 4V heads but one is an open chamber set. But I should have a backup if needed. Also the machinist I found only 5 miles from me had races the 351C for many many years, so hopefully that experience will add to his machining capabilities. And do vaguely remember the there was a setup that didn't require pushrod guides. I'll look at that also.
Bdud, never thought about a beehive breaking....will definitely look at the conical springs or just go with a more conventional spring that has a damper which if the main spring broke might still save the valve from major damage. Thank you, great advice!