I need a little help on the cooling system for the GMC inline engines. I am putting a 302 in a 52 1/2 ton P/U and want to use the original AIR FLOW heater (with the temp control valve on the firewall). The 302 that I have came with the special fittings that come off the thermostat housing and the waterpump for coolant bypass (connected together with the short section of hose). My question is this:
If I leave the special fittings installed and connect the heater hoses to them, will my heater ever get warm? If I do not install the special fittings and connect the heater hoses directly to the thermostat and water pump (I think this is the most commonly found setup), will the engine still warm up properly or will I have hot spots and head warpage?
This is assuming that the heater control valve is off and not letting any water into the heater core to recirculate to the waterpump(summertime). During the wintertime water would be allowed to recirculate because the valve is open.
I don't remember seeing the special fittings on any of the 228 or 248 engines. Does the 302 need these fittings for recirculation because of the bigger c.i.d?
Any ideas or thoughts on this would be great and if the question needs more clarification let me know.

"The Operation of GMC trucks is normally smooth and steady, with no loud rattling, knocking or unusual noises. A good driver will quickly become accustomed to driving a GMC truck and will get the feel of his vehicle regardless of his engineering knowledge."-TM10-1563