Not 100% certain, but almost, that an 84 ECM will work too so long as it's a Cali truck. They too had the Electronic Quadrajet with the AF Mixture Solenoid.
I can't think of a reason the V6 ECM won't work. To the best I can recall, the ECM for the CCC just controlled Electronic Spark Control with the knock sensor, and the AF Mixture Solenoid on the E Carb. If his had the E Carb too, I'd think it would work. All its for is advancing and retarding spark advance though the ICM and the AF mixture. Those items don't have anything to do with the # of the cylinders. Maybe I can find something, IF I can find my old CCC GM book.