Late to the party here, take a look at what Jerry at Clevedon Steam has for fittings:
https://www.clevedonsteam.co.uk/products.html
He is in the UK but have found his shipments to me in Canada are quick and reasonable.
Jerry is a great guy. I order from him all the time and I get my shipment in a week which is really good for England. I recently ordered a safety valve for a boiler I just bought and he even set the pressure for me so I wouldn’t have to do it.