Hi Paul.
I personally wouldn't disconnect at the oil cooler. The coolant rail pipes that travel across and above the front sub frame supply the oil cooler, so looking into the engine bay from the front of the car on the right hand side directly below the expansion tank you should see the 2 pipes travelling down connecting to that rail.
For the later type oil cooler, perhaps purchase 3/4" (19.05mm) diameter 180 degree aluminium or stainless beaded bend to bypass here.
Choose size and bend angle from list here
https://www.autosiliconehoses.com/al...nium-tube.html
I don't know what the internal bore of the early type connection to the oil cooler is at present I'm afraid.