thanks for the tip on the insulation tape. I was able to track down something at Rick's Camaro that looks like the same stuff. http://www.rickscamaros.com/camaro-air-conditioning-insulation-wrap-evaporator-core-upper-tube-1967-1969.html
any ideas on where to find the sealant goes on the firewall and inbetween the two pieces of the evaporator casing? Rick's also lists Evaporator Case Seals, but shows them discontinued. I haven't been able to come up with the correct search terms to "uncover" a similar item at other online places.
The "goop" wrapped around the evaporator, I replaced mine with Four Seasons's insulation tape #59010. It may be the same as NAPA #TEM 209491.