Trying to fix leaks at my Club and have to cut into 85mm? cast iron pipe from gutters to rod it. Pipe is between old building and extension and only place I can access is in beer cellar (rotten job but someone's gotta do it). Before I cut I need to get replacement section (PVC?) and couplings but nearest I can see is 110 mm pipe. Old bit of building is 70 years old so assume current pipe is same age. Any suggestions welcome. Sorry, one man job can't justify assistant in cellar.