Probably best to search for a new unit: https://www.stein-dinse.biz/product_info.php?products_id=322555
I was able to change the broken front glass on my 03 Rosso Corsa with that from a sport...now I'm not sure if it would work for your situation. Stock replacements were few even 15 years ago. I remember having to slowly use a dremel with a cut off wheel to remove the glass from the sport headlight. I wanted the clear lens off the sport, I think (this was years ago) that I was able to seal the new lens back on my existing lemans bucket, but the sport unit was trashed in the process of getting the glass. Doing research back then, I believe a early to mid 2000's BMW headlight module could replace the stock unit, but it had fluted glass, unlike the clear lens on the MG. I run a plexiglass cover over my headlight now to ward off rock strikes.