good progress to be sure mike ! when you first mentioned your radiator, the first thing that popped into my mind was a mustang unit. i think you will be good with the open hood sides provided you use an OEM electric unit that will pull a ton of air, such as a taurus or t-bird setup with a 3.8[?] engine or similar. make sure your electrical system is really up to the task, as these fans take a huge amperage at startup. above all, don't use a generic aftermarket fan. these things don't pull anywhere close to the advertised cfm of air they claim, and i have seen almost all in use at one time or other. the problem with using a mechanical fan is usually, the engine is mounted low in the chassis, which makes the pump driven fan also low, positioning it low on the incoming water from the top neck not cooling until the water is halfway through the core. you may not have this problem depending on the way the mustang radiator is mounted. if a guy runs a big diameter fan, it's possible to have interference with the radiator support or the front crossmember, depending where the engine is positioned. i like the heater choice ! what core application did you end up using ? and finally, the dodge pickups in the 60-80 time frame used the type heater valve you were seeking. i still see these occasionally at the swaps new, and pick 'em up for only a couple bucks. sometimes you can find the "fitzall" brand of controls as well for a buck or two.