225 /6 and trans value?

Probably worth $500 for future use, but unlikely you could sell for >$100. One advantage of staying w/ factory setup - slant, auto, drums, 7.25" rear, 4 door is cheap parts. The rare and desirable parts command big bucks, like a 4-spd tranny or Sure-Grip 8.75" rear w/ low gears. That is why some Darts are worth $90K and others $2K, though both may look similar externally.