I'm going to say that 1971 was the change over year Mopar went from the earlier colors on all the SB to blue, not turquoise work
BTW, I've used most of the popular engine brand paints and I have not seen or heard of the original Mopar green, turquoise engine paint, turning to blue when heated confused

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)