Thanks Metman,
You touched on the point of Si having an influence on the melting point.
With ~3.5 to 4.0% Si and 0.8% Mo, I believe this throws us to the other side of the Eutectic. Does this sound correct?
What Carbon percentage gives the most favorable results as far as shrinkage goes, and at what temperature should the metal be poured to minimise shrinkage. How significant is the difference in melting point between an iron of 3.2%C compared with 3.8%C?