After several headaches with the OEM cobalt cables and some tubing I nicked from scrap at work, I used this brake cable kit instead with my OEM parking brake handle and DF parking brake kit:
330-9371 Parking Brake Cable Kit Fit for Wilwood 110" Long Cables with a 97" Long Sheath, Universal Emergency Brake Cable Repair Kit
https://a.co/d/jiJrO0C
This one is a knockoff and is half the cost of the Summit kit and is basically the same product. Don't bother with the OEM cables.
I also got the brake handle connector and ran it to a red LED I installed in the dash, with positive wire running to a fuse tap at the BCM temporarily. When the parking brake is pulled, it grounds the connector, completes the circuit and illuminates. I'll make a permanent run later. Thanks Rttoys and Joebob and others for the idea.