Basil himself does not make replacement parts this is out sourced , but yes he then uses those parts for restorations but mostly in clear glass , the colour would be very difficult to match and you would have to make a batch of glass , very very expensive,the part would most likely have to be free formed , ie not in a mould and the result could be very hit and miss , too many possibilities for the replacement to look pretty dreadful I think ,the area around the remains of the original handle would also have to be prepared to receive the replacement part , ie bits ground off to give a flat gluing surface,
I just see lots of problems and huge cost for the attempts , so I can only say again, what i have seen done to glass items with replacement resin parts has always looked very good.
cheers,
Peter.