Can't you just drill out the broken guide pin and solder in another one. Might take a bit of fitting to make it slide smoothly after it's in place.
But why bother with all the cross pin, blind pin thing.
Just get the old piece out and put a new piece in. Even if you drill the hole in the ejector a bit bigger than the old pin, turn a piece to fit the ejector and step it down in dia on the breech side for the correct 'pin' size.
Before you reinstall the pin, you can fix any damaged from the blind pin popping thru the surface. Just clean it good with acetone, flux it and lay a dot of hard solder (High Temp Silver Solder) in there and it'll draw right into any small cracks or crevices. File and polish it smooth.
A tiny discoloration in the steel from the silver solder is all that'll show. It'll work two more lifetimes and more w/o a problem. Then fix that pin and take it hunting.
