You can still use the blacked out rear window trim if you want. GM just painted the regular trim. Strip the paint and it's nice and bright. Probably not worth the hassle, but I'm just sayin...
You can use the 1/4 windows and the rear window trim off either another Monte or a Grand Prix. They are the same.
Both of those don't have a lower piece to the rear window trim, it just butts up against the piece between the window and the trunk lid. Yours will probably have mounting holes or whatever for your vinyl, so snag that piece too if you need it.
Although to correct what was mentioned before, the Cutlass and Regal 1/4 windows are in fact not the same.