1993 Cavalier 2.2L Replacing head.

College beater, replaced the head gasket when I first got it. Fantastic little car. From 160k
to 210k miles with a partial miss, recently developed a more serious problem and missed
a lot harder. Went from 25mpg to 17mpg. Ran compression check and 3 was showing
much lower than the others (iirc it was below 100 and the others were around 145). So I
grabbed the head out of the salvage parts car (70k miles), had it resurfaced, and I'm in
the middle of swapping it into the beater (About to reassemble with new gaskets,
resurfaced head, all that jazz). Looking at the underside of the beater's original head, the
1/2/4 valves are grey, and #3 is black.

My question is could something else be at fault? My friend is concerned that perhaps the
injectors could be part of, if not the issue?

Secondary Questions: Should I get new rocker arms or pushrods? Any recommendations
on what to look into possibly replacing since I've got easy access to most of it currently.
I've got spark plugs and a serpentine belt on the list so far.