Actually I was thinking about that too earlier, really! I just thought that 2 adapters would be un-neccesary, and why would you be going from 3.175mm to 8mm?
I could only find 3.175mm to 5mm shaft adapters, 3.175mm to 8mm is a large jump. You might be better off getting a different drive shaft, or drilling the hole out.
Welcome to the forum!