Thanks for the help everyone. This was definitely a project that took a great deal of patience and persistence to get a good result. I learned a lot from it and I think I did as good a job as possible. I've never completely torn the dash of a vehicle apart before, and it sure was a challenge. My hands got pretty cut up, especially during re-assembly; it sort of looks like I was fighting a cat.
I made some noteworthy improvements to the heater box while I was at it. For starters, all of the old foam seals were
painstakingly removed and replaced with new seals. I used billiard felt for some of the flaps with excellent results. I glued it on using contact cement, again with excellent results. I used foam weatherstripping tape for some of the seals inside, and in one spot I used a different cloth type material. All of the foam seals that seal the sections of the heater box together were also shot, and they were re-done with caulk. All of the ducts were cleaned, a new heater core and evap were fitted, and off we go. The Nissens brand heater core had a notable difference, if you plan to use one you should check out my YouTube video of the heater box. You can also check out how awesome billiard felt is for the ducts and get a good view of the AC recycler flap working.
Cheers!
http://www.youtube.com/watch?v=rRP892ytqXg