I just saw your most recent post, but had missed your original question last year. By now, you have probably long since solved your problem. But just out of curiosity, what was interfering? Sorry, but "elbow pin interferes with the motor housing" didn't mean much to me. What is an "elbow pin"? Where on the motor housing did it encounter interference? I don't suppose you have pictures.
I have put e28 motors into both the F and R window regulators on my e9 and don't think that I encountered the sort of interference that you refer to. But then, since I don't really understand your issue, I can't say much more than that I didn't need any washers to space the motor back from the regulator frame.
