Well guys, I finally found the problem!!!
Upon removal of the water pump I noticed something was rattling inside it as if marbles were inside it, so I removed the back cover/plate and found the impeller spinning freely on the WP shaft! How in the hell was this truck not overheating!!? Upon closer examination, I was spinning the pulley by hand and noticed that the impeller would spin a little bit, which explains why the truck was not overheating and was actually moving some coolant across the radiator but did not have enough pressure to circulate it through the heater hoses and core. Off to the parts house to resolve this issue once and for all!!
Outcome to follow, stay tuned...
Upon removal of the water pump I noticed something was rattling inside it as if marbles were inside it, so I removed the back cover/plate and found the impeller spinning freely on the WP shaft! How in the hell was this truck not overheating!!? Upon closer examination, I was spinning the pulley by hand and noticed that the impeller would spin a little bit, which explains why the truck was not overheating and was actually moving some coolant across the radiator but did not have enough pressure to circulate it through the heater hoses and core. Off to the parts house to resolve this issue once and for all!!
Outcome to follow, stay tuned...
Heater works wonderfully after a new water pump was installed and cooling system was properly purged. I went ahead and did the Mark VIII efan setup as well and it all works extremely nice. Thanks to everyone involved in this matter, have a great one 
