If it were my vehicle, I'd pull the pan and take it to a good machine shop and let them make the repair. I would envision them simply over-sizing the hole and installing a new drain plug to fit the new hole.

It's my understanding that BMW used a GM 4L-30 unit in some of their cars. This may be what he has and they ain't cheap, not that any of them are.

If you go this route, be sure to thoroughly clean the inside of the pan to ensure any metallic debris stirred up from the surgery is removed.

My 2 cents.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"