Cleaning used short block

Before installing the cam:

Get a wire coat hanger and straighten it out. Use it to poke through all of your oil passages after blowing them clean with compressed air.

Stick it through the holes in the top of the main bearing saddles in the block and make sure that it goes all the way through to the cam tunnel.

Also poke through the oil hole in the head face to make sure that the oil holes in the cam bearings are also not blocked.