By the white earlobe, I'd say those who advised you that he's a Cal. Grey are correct. I'm the fellow who wrote the article on California Greys that appeared some years ago in Countryside & Small Stock Journal Magazine and also the fellow whose Cal. Greys appear in the Storey's Illustrated Guide to Poultry Breeds. I have raised them for twenty years and my grandfather raised them since the 60's.
The Calif. Gray is a truly wonderful bird, however the only two hatcheries I'm aware of who have true Calif. Greys are Rockin' Rooster Ranch and Privett. I've had birds from both places. My observation is the R R's are a might heavier.
However, the Cal. Grey is not a heavy bird. It is a leghorn in the truest sense. If you want to raise Cal. Greys, then you have to breed them to Cal. Greys. You could breed him to a white leghorn or a HiLine. That's how to get a California White. Also, if you would breed the Cal. Grey to some Cal. Whites, some of them will throw back to Cal. Grays.
I'd advise you to get some more from one of the two hatcheries I've mentioned. I've had them from a number of hatcheries and those two hatcheries are the only ones I've found who still have an actual line of Dryden Cal. Greys.
The California Grey was originally bred by James and Horrace Dryden. The Drydens owned the Dryden Poultry Experiment Farm in Modesto, California. The bird was bred as a dual purpose breed. She's a great layer of white eggs. Being a touch heavier than the white leghorn, they're a good layer in the winter. You're left with a fine bird when she's old to use as a stewing hen. I've found them to be an excellent layer and a good seller to the Asian market when she's done as they want a colored bird. It for sure is the best colored feathered white egg layer you'll find.
Drydens didn't believe in creating birds that were just "fluff and feathers" preferring the characteristics of a good layer instead. Therefor, the California Gray leghorn was never accepted by the Standard of Perfection. When small farm flocks began to be taken over by the big laying factories in the 70's, most Calif. greys disappeared as the big laying houses preferred a smaller bird for cage layers.