[Bigdav160]

GM's first CCOT (orifice tube) didn't arrive until 1973.

You should NOT have a low-side accumulator with a TXV-POA system. The high-side drier (on the core support?) is correct. It ensures the TXV gets nothing but liquid refrigerant.

The oil on the foam near the POA is a sure indicator of a leak. The line connections, while hokey looking, don't appear to be leaking. Can you trim the foam back to expose the outlet of the POA. That small copper line doesn't look right and would add a restriction.

How much refrigerant are you putting in? Front and rear A/C is a big system.