Help with a new to me 408

I never could get rear main on mine to seal until I put thin film of RTV between rear main cap and block. Otherwise high oil pressure pushes oil out between cap and block appearing like a seal leak.

No way I would build an engine with flat tappet lifters given the risk of wiping a cam. Roller lifters in my engines only I don't need that level of grief. Wipe a cam back to square 1 total tear down start over