The red on this engine is the early rocket red, it is unlike the series 2 rocket red.
I have a genuine 6/1973 308 and it has the early rocket red. I also have a 8/1974 kingswood with a 202 and it is painted in the series 2 rocket red.
When the specific change over happened I don't know.
One thing is for sure if you use the wrong colour it does not look wright.