The Santorin galley port is the same size as the SM. It may be no use for you but perhaps someone else - I had a mould made for one in Trinidad at Peakes boatyard, a fibreglass chap in a shed at the back of the yard. He still has the mould. I know Amel no longer have them or a mould.
Maybe a local fibreglass place could also make a mould. I paid for two (one for the aft heads & galley) and told him to hang on to the mould and check every Amel that arrived! I should have bought the mould off him too!