A converter is a piece of hardware you don't want to cheap-out on. I bought a 904 converter from a trans shop in San Antonio 30+ years ago because I had no money. I also did not push the car hard but rather drove it easily as it was the only one we had. If you have a lead foot, go with a premium...
The Carb Cheater is not crude at all. It does, in fact, monitor the AFR and adjust to bring it within the range specified by their phone app. I use the CC on my 70 Duster and it helped me dial in my AVS2 to be spot on. Besides adjusting the AFR, the great thing about the CC is the ability to map...
I put a 22" cold case in my 70 duster and tried putting a mech fan/clutch in. Would not fit at all (hit the core). Pulled the rad and went 26" 3 core champion. Worked great with contour fans.
I had a Champion in my 70 Duster and was able to put on a fan (OE style with lots of pitch compared to aftermarket) and the 2947 short Hayden clutch. It fit, but not by much. I modified a shroud I got from Mancini Racing to fit. Cooled just fine. My current Duster has the 3 core Champion...
The CC radiators have a very fat core (3" on the one you linked to) so you may have problems with clearance between the core and water pump snout. I sure did, and had to go to a Champion radiator which has a 2.5 core thickness.
The solenoids do not have the power to increase the throttle by themselves. They only work when first energized then when the user opens the throttle it will keep the idle higher until it turns off.