318 hydraulic lifter preload.

If it hasn't bee run yet I'd pull the heads, have them milled .020", then reinstall them with the gaskets you have. Then you should be ok with the pushrod length you have assuming there's not a lot of lifter bore leakage from wear.

I'm with RRR on his assessment of the quality of work. But - at this point, it's a place-holder. Fix the problem, no need to redo everything. You need a flat head surface, and you need the effective length of the pushrods you have lengthened. Both are accomplished by milling the head. Go more than .020" and you might have intake fitment problems - so don't get carried away.