The job wasn't as bad as I had feared. The sandwich adapter came out easily with the hard lines still attached. They're rubber where they go into the cooler so that helps.
I had put a metal spacer - like a giant washer - between the block and adapter. Seemed like a good idea at the time since it came with the kit. It looks like the oil was getting past that. So I took it out. Reinstalled the adapter with a new paper gasket and O-ring. It is not leaking at this point in time.
The fuel pump switch is leaking like a sieve, and dripping on the exhaust, so I need to do that one next. Out of time for today but I think I'm gaining on it.
Further research on oil pressure revealed that my pressure is fine where it is.