source for exhaust valves

I'm having a turbo head (1986 turbo) rebuilt at a local machine shop. He is having problems sourcing exhaust valves that are turbo specific. Can someone give me a source and/or a part number for these?
thanks,
david

I imagine you would have a hard time finding OEM turbo exhaust valves.
Years ago I,and others, were using stainless. They were available on Ebay. Maybe ask Boport what he is using and where they get them.