I've reared lambs on Jersey milk, as have many other farmers. You may be right about the A2 thing - in which case, Shetland milk would probably work too.
The two things I found were that they need a lot more quantity of Jersey milk - half as much again as powdered ewes' milk - and they didn't seem to be able to switch back to ewe's milk. So I used to feed half Jersey and half ewes' milk until they were past the point of being adoptable, so their systems were used to both, in case a foster mum came along.