Pickedup a one-piece rear main seal block yesterday. It had what looked like the bosses for the roller lifter retaining bracket. When I pulled the lifters they were flat tappets. Block was 4-bolt with a windage tray that was supposed to be from a 92' truck. Can this block use a stock roller lifter?

 

Yes, when used with the spider thingy or lifters with link bars.

Late model truck blocks have the roller cam provisions, but only had flat tappet cams from factory. That's what I have in my car (91 truck block) but running roller cam setup.

 

If the machining wasn't done for the roller provisions, the cost would lead me to just go to a flat tappet cam/lifter set-up.

 

By machining you mean what? Machining of the lifter bore area or to secure the spider? I will clean the block this weekend and start measuring wear and tear. This engine will be a drop in replacement for my TPI 350 that leaks oil from every gasket a runs very slow at 4000' altitude.

 

Both