I just want to know, what bolt engines are on the '91 Camaro RS (V6 Engine), I'm assuming 4 bolt?

Also, since the 455 is one extremely old engine and doesn't use engines, could I keep the same wiring harness on my Camaro? But I don't know how the old engines work...What would I need to end up doing?

"4-bolt" refers to the number of main bearing cap bolts. Doesn't have anything to do with how the engine is mounted in the car.

A 455 is either a Pontiac, Buick, or Olds engine. They are all different. There is a sticky in the top section of this forum about installing a Pontiac engine. Otherwise, you're pretty much on your own fabricating what it would take to install one.

I'm talking about the Pontiac 455 - would I need to replace the wiring harness is my question though?

Replace? No.

Modify? Without a doubt.

Read through the sticky.