Summit Racing also carry a suitable fitting under
https://www.summitracing.com/parts/ear-940006erlp
Its an Earls product, sold as a pair...
These use a flat crushable washer instead of an O ring...
Work well as pressures well under 100 PSI in clloer circuits, even if you use lock up convertor...
Now back to assembling my new trans...6L80E...to go behind my 6.0....