its been done b4. probably best bet would be to adapt some omega or carlton running gear to fit as the 4x4's aren't constant 4x4 so you would have no drive if you simply removed the front drive shafts. ive seen a picture of a cavalier converted to RWD the engine was logditudinally mounted rather than the usual so you would probablt have to do this unless you went down the route of simply locking the transfer box and removing drivshafts from the front but thats cowboy as **** lol! it would be to much work if not near enough impossible to convert a FWD cav to RWD
Im sure someone has converted a cav to rear wheel drive by side mounting the red top and using a modified Manta set up, you need to have a 4x4 though as you need the rear prop tunnel. Will dig around and see if i can find it.