With the exception of the rear quarter window trim, most everything should swap over assuming that both cars have the same roof (t-top or solid roof) and the same seat style (bench, split bench, buckets).
The only challenge I can see.....is that if you are using the cutlass dash and instrument cluster, it will take some work to blend the cutlass dash harness with monte body and engine harness. Shouldn't be too difficult with wiring diagrams for both cars.