If your using that box etc just leave the driveshafts attached to the hubs on the subframe, drop it all,bin the 8v, bolt new engine to box and refix subframe with everything left on it. Makes it easier to clean up down there and replace things like rack bushes and cleaning bay etc. Unless you wanted to leave the subframe in, which will require splitting the box and undoing hubs etc? Your call but I'd dump it all out. Thought u had a complete donor mk3- bolt that subframe straight up can't ya? again without splitting anything?