I have a 350 block with the casting number 14093638. This block came from a 89 1500 pickup with a flat tappet cam. Mortec list this block as 14093638...350...87-95...2 or 4...Roller or flat tappet cam one-piece rear seal. The block has the bosses in the lifter valley for the spider and is machined for the lifter retainers but the lifter bosses are not drilled and tapped. I have a 87 305 roller that this 350 is replacing. I wanted to use the spider and lifter retainers from the 305 with a zz4 cam and new lifters. Can I just drill and tap the bosses to mount the spider or is there something esle that would need to be done to use the factory roller setup?

 

If the little towers are present in the new block, go ahead and tap them for the roller hardware.

Don't forget, you will need the factory roller cam retainer plate on the front of the block as well.

 

I did the exact same thing go 4 it itll work