Hmmm. I can see why you're asking @ 100 quid cost....
Mugello use Graded pistons, so you really need to establish which Grade you need to establish the actual size/tolerance based upon the nominal diameter.
You might then be able to select an alternative but I think you’ll be lucky...
There may be lots of ‘cast-offs’ available via the members of this Forum, though, so it may be worth asking once the Grade has been established.
BTW. Bear in mind that whatever piston you may opt for, the rings need to be suitable for a plated bore.
It may be the best option to take a spare, cheaper cylinder kit just to get you home. The chances are, you probably have one knocking about, already...
