Thank you for your reply.
I know that the uniflow valve has been out of production since the 80's. The newer capilano helms got the relief valves installed internally now. But I've got a single ram on my outboard, and the newer capilano helms seems to lock up when they are used in combination with unbalanced cylinders. I've borrowed a 275V helm and the uniflow valve, and that worked like a charm, so would really like to get my hands on a model 50 valve