Bill now owns the car I built. I made a “donut” shaped ring that sandwiches between the spare tire and the fiberglass engine cover. Bill has pics of it and there are other pics on another thread on this Forum.
I’d stay away from using old upholstery from MG MAGIC or anyone else. Keep in mind you are still buying old material. Even if it was never used, it’s usually dried out and will not last long.
My interior still needs carpet (I’ll fabricate it) and the top will get replaced by one made of Stayfast fabric or I will install a “zipped down the middle” tonneau cover made of Stayfast. Again, made by the local upholsterer. I have no side curtains.
I wish Southern California was a day drive away…that’s the car freak capital of the planet! I’m sure you can find an upholstery shop that could re-do anything on your MG.
Hope the damage is not too bad on your toy!