jbartos, thanks for reply.
Identified a few different series having 20ga pin and for 20 ga wire, the most economical seems to be a MIL-C-26482 series 2 (insert arrangement 20-41) connector using MIL-C-39029/9-132 copper pins, MIL-C-39029/9-133 constantan pins, MIL-C-39029/10-138 copper sockets and MIL-C-39029/10-139 constantan sockets (this series uses an anular crimp to native thermocouple wire). I have no criteria driving the use of MIL-STD parts and where possible will use commercial equal. Another vender is selling a system compatible to MIL-C-26500, but are more expensive (and I rather have the bayonet coupling on the 26482). Found a d-sub with TC native alloys but am worried about the robustness. The connector will be used with type T, in the future will likely expand to type K.