Shouldn't be a big deal as said you have to swap all the drivetrain over. I've put my 6600 triple group on a couple of different late '80's early 90's frames and have never had to cold set them. A couple things I did have to do was file the slots on the 6600 brakes longer as the reach wasn't quite enough even on original 700 wheel bikes and drill out the fork and brake bridge for recessed nuts as the originals were nutted brakes. You may also need to get cable stops if the original had downtube shifters.