318 LA rebuild after losing a valve seat

Also the lengths of your push rods as compared with the above stock '69, 318, 302, 340 cam build. These stock pistons with the valve reliefs sit .040 in the hole.

Your Scamp 318 build with the flat top pistons sitting .077 in the hole.

Same same as far as valve to piston clearance is concerned, considering the valve relief pistons in comparison to your new flat tops.

Thinking you can use your stock length pushrods here.

Put a wad of plumber's putty on top of one of the pistons, bolt on on one head with head gasket just snug. Drop in a pair of solid lifters with the stock valve train, roll it over and see what you got for piston to valve clearance.

Valves not touching the pistons, that is a good thing . . .