I was doing some measuring on my '82 Camaro the other day, which is much the same underneath as your '87... With a bit of trimming on the inner fenderwells, the 9.5 wide IROC wheels will fit in there just fine, with some very careful measuring of the backspacing, a 10" wheel should fit.

On any 87 with the torque arm being the only upper link and going to the transmission, and just the short lower arms you do have a few options. On Joe's Camaro, we put a set of UMI lower arms and torque arm in, along with their Frame ties. It's a very nice setup, and should work great. Unfortunately the car won't be on the streets til spring so at this time I can't tell you just how well it will work. My Camaro will be getting a 9" rear, coilovers, and a triangulated 4 bar. Using a triangulated 4 bar will require loosing the back seat and adding a 6 point roll bar with some bracketry to tie the upper arm brackets into the bars and tub.... UMI and numerous other companies make adjustable lower arms and a torque arm and mount that moves the forward attachment point of the torque arm from the transmission to the crossmember, this could be another option.... If you want to see their stuff, check out sales@umiperformance.com. They are heavy duty parts and built quite well with polyurethene rod ends which IMO are much better then heim ends for a street car....