Yes, I cleaned out both driver and passenger side vents and cowl a while back. Just to make sure the control valve wasn't the problem I took it out and put a straight piece of copper pipe in. I blocked the radiator with cardboard and now the engine temp is up toward the higher normal range, which does help some. My AC unit is disconnected, no compressor any longer.
Thanks for all who replied. I'm just going to resign myself to the fact that this truck just won't throw heat out like my '65 and '66.

Tom