I have a '79 244 that has been parked a while (bad clutch and now an interior science project in mold). I can't find anything that says yeah or nay (or infers) that the M46 out of it will fit to the B18 and/or into a 122s (without hammering new bulges in the sheet metal).

So will it fit?

 

Sorry but I can't really tell you for sure either. The 122 was way before my time!!!
I was 5 when the car was new.