I-6 heater problem

[gearboxx70]

Forgive me if I'm beating a dead horse here, but I did try to search for answers first...

I've been having problems getting my heater to work. The truck is a 67 with the 292 I-6/ SM420, non-AC cab.

I cleaned the mouse nest out of the heater box. I installed a new water pump. Checked all the control cables and doors. Installed a thermastat (since there wasn't one in there when I got the truck). After all that, the heater blew "warm" air. It had a hard time defogging the windshield.

Yesterday, I replaced my radiator. (Griffon "Direct-Fit" radiators are anything BUT direct fit! And this is my second in 6 months!). While I was in there, I put in a 195* thermastat (as was suggested to me several months ago). The thermastat and electric cooling fan work perfectly, but now the flow to the heater core has slowed drastically! I waited for 25 minutes for heated coolant to reach the heater core, and at least another 10 before any heat was felt at the return hose. Yet, even after heat was felt at the return, there was no heat blowing from the heater in any direction.

The truck is my daily driver, and there are no signs of rodent activity. Before the thermastat was changed (a 2 hour difference in time), the heater was stil blowing "warm" air. After the change, to the higher heat thermastat, no more "warm" air.