Advice on a 440

Another method to check V to P clearance without clay. Assemble head with light springs, just enough tension to hold the valves in place.
Instal head with gasket [ or equivalent thickness ]. Install prods, set lash etc. Slowly rotate engine until both valves are open at TDC. Push the rocker down & that is your clearance. You can measure the distance with calipers. 0.100" int & 0.125" exh are safe minimums. If you are close to these numbers, then the int valve should be checked a few degrees AFTER TDC & the exh checked a few degrees BEFORE TDC.