I have heat! Now measures 124F when at running temp on HIGH.
The DIY would have worked if I was a little more patient or skilled. The bushing at the bottom of the mixer door axis was cracked, causing the door not to pivot when activated by the servo motor. Not sure if I damaged it during reassembly (it was very tricky to remount the door), or if it had been broken all along. The problem area is located under the circle accessed from the under dash in passenger footwell:
The indie was able to repair the bushing - hopefully - for a long term fix. They had never heard of this foam/mixer door problem, so they learned something. Maybe because it is not as common in colder climates. My car was born and raised in FL. Cost was 4 hours labor.