engine color question

Pay attention here now guys. If you will notice Bullitin # 1575 was dated on 9-6-68 relating to the factory color change for these cars and trucks. Now if this bullitin hit the plant in late 68 then as usual, it will take, at minimum, a month for this to be all sorted out and get into the mill so it is very likely there will be some red 340's put into some early 69 cars before the stock of red motors ran out. I'm very certain that they wouldn't repaint the red motors to Turquoise so as to comply with the bullitin. So from my observation an early model dart could be correct in having a red motor. Sound right?
Small Block

I believe my car is an early build, due to the fact that is does not have head rests. It has the original block and it is turquoise. Where on the build sheet or fender tag would the build date be indicated?