318 4 barrel kickdown linkage

All I need now is a kick down rod that goes from the bell crank to the csrburetor

I saw an extension piece
Edelbrock 8003 and 8004
Those are too small

I think it needs to be 3/8 fine thread
So far I haven't been able to find one. I'm thinking maybe take it to a machine shop and having it done. It I'd rather just get an original piece or get the extension