Hi ,
I didn?t realise you were new here !!-so welcome aboard !!!!I don?t have a carb for that size MV but being a fairly common engine one will show up easy enough- there was a whole engine sold at Allora rally last weekend for not much money. Watch eBay they will be on there from time to time.
Where abouts are you from ? There may be people on this forum in your area
Cheers Justin