Billy, i think that itŽll be all good, with that Ford Dark Blue engine paint.
I donŽt think a specific paint was used through all the years anyway, since colour does variate quite a bit inbetween the engines here.
What you should do though, is to ensure that youŽre "cheap" when it comes to paint.
If you coat it too genorously, youŽll hide the sandimprints on the casting, and make it a smooth glossy surface, which they never had originally.