sbc plastic timing cover and short w/pump

I'm guess'n that they work together but I've been wrong before..
engine has'n got here yet to look at old and new..
hoping they do.. or I'm s.o.l. with truck brackets..
anyone know the difference in hight off the block face, plastic vs metal timing cover..

per the dealership parts guy the vortec 350 #12530282 is two bolt mains and single chain and the 12530283 4 bolt main is dual chain, so the cover could be a standard sbc cover..
anyone know??
thanks