I have a '90 RS and was wondering if the gound effects on a '91 could be placed there instead.

 

It depends on what the other ground effects came off of.

If they came off a Z28 most likely not (every is mirrored on bolting it on, ex: metal plate from back is in front fender )

If they came off of another RS or IROC-Z or a plain camaro they should work

 

Welcome to the boards
You can install 91-92 ground effects onto your 90 with little modifications. Mainly you will need the front spoiler, side ground effects, door gfx's, rear quarter gfx's and HITHERE 91-92 rear bumper.
This comes up alot, try HITHERE search this button at the top of the page and you'll come up with may posts with lots of detail in it. HITHERE dont want to type it out since it will just the the HITHERE thing and mess it all up.

 

II did aa search using GROUND EFFECTS CONVERSION, and just searched this board and came up with this: Since the [] code isnt working at the moment II cant display the link to the page