Synthetic would require a crazy expensive mold. So that's not going to happen. The most obvious "synthetic" stock would be a one off fiberglass, carbon and epoxy over foam core with the work molded over some manner of insert for the action well. Still very expensive and far more than the cost of the rifle
Aluminium would be hellishly heavy compared to the wood stock. And cost a bundle to fit the barrel and action. You really don't want to pay that sort of cash.
If you want to hunt with it I could see making a more contemporary wood stock if that's your thing. But I think wood is where your desire will have to be content with since either the composite fiberglass or carbon and epoxy over some sort of foam core and fitting the parts would cost a bundle. Probably more than the cost of a machined aluminium stock.
