Heater Help???

[big dump]

So, I'm trying to get some hot air blowing in my '72, and I've got a real head scratcher in the works. So far, I've flushed the block, put in a new T-Stat, water pump, and had the radiator dipped and re-built. I also flushed the heater core, which to my understanding is just an in-out, so if it flushes and water passes through without obstruction it's good right? The inlet hose for the heater core isn't getting hot. It gets slightly warm to the touch, but not hot like the upper radiator hose. I'm certain there is water flowing through it, just seems like it's not hot enough. I would think that the inlet for the heater core should be really hot. I removed the vacuum valve, and replaced with a straight through just to make sure that I had hot water running through the core. Any suggestions? I'm really starting to get frustrated with this because its supposed to be such a simple system. I've got some issues with the cables and doors inside the cab as well, but if I understand how this system works, the core should be getting hot water through it all the time, and when the blower is on, the air should be hot. The vacuum valve is to shut off the hot water going to the core, correct? Help me out here guys.

Thanks in advance.