I know what you have there. It will be difficult to find that part if not impossible. If you did find it the cost will probably be very high unless you find one on Ebay. If it were me I would replace the gas train on the unit. That means getting rid of the safety, valve, and the electric gas valve.
I would replace with a Honeywell or White Rodgers standing pilot gas valve. Naturally you may also have to replace few pipe nipples to make up the gas train.
You will also have to make sure to wire all the safety controls and be sure to check to make sure the system is 24 volts. If not you may have to add a transformer.
That picture is so small I needed my glasses ands cheaters to make it out. I also believe that heater is older than 30 years.
Send a bigger pic to
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