FWIW...I agree that is most likely out of a 71.

Matching the VIN to the engine assembly date may help.

for 69, VIN 219*** would have an SPD of 212 - this would be before your engine assembly

for 70, VIN 219*** = 410, again before your engine assembly.

For 71 VIN 215*** = 512 and 225*** = 602. So the VIN range and your engine assembly date fit best with a 71 model.

This leaves GTX's, Road Runners, Super Bees and Charger R/Ts as possible donors.