Actually grey and partridge would mix better. The only difference between partridge and grey is the silver/gold gene. Pair a grey hen with a partridge cock and the daughters will all be partridge; the sons golden (split S/s+) partridge. Pair a grey cock with a partridge hen and all the daughters will be grey and the sons golden partridge.
For the 2nd generation take the golden partridge boys and pair with a grey hen for 50/50 grey & golden partridge boys and 50/50 grey & partridge girls. Or pair the golden partridge with a partridge girl for 50/50 partridge & golden partridge boys and 50/50 grey and partridge girls.
**** note that my use of the term "golden partridge" is based upon golden being the common term for a male who has one copy of silver and one of gold, not upon a recognised variety ****
Sonoran- I have heard the term 'gray partridge' bandied about for those cockerels I've seen posted as 'calico' recently, with one person saying she had exhibited a cock of that color under partridge successfully.