Hello!
It's a very nice looking drum and the set Dule posted link to just made my eyeballs pop out! I've never seen so beautifully preserved Amatis! I never thought much about orange sparkle but your drum and Dule's post might make me change my mind.
Now... I think you're better off with inoriginal hoops and strainer system, because the old Amati strainers were incredibly simple, almost primitive, and, at least to me, absolute and horrible pain in the arse to set up. I have to warn you, though, that you might still have some problems with the drum - edges were not really perfect and snare beds were shoddy. At least the second problem can be solved easily with a piece of sandpaper, though.
To the number of plies: Amati indeed DID make 3ply snares, but they're VERY scarce, as they are one of their oldest models. I have seen 3ply 5" and 3.5" snares, but I think they belonged to their older sets with different logo setups, often mufflers on both sides, and, on the really old ones, even with nickel-plated hardware. I had the opportunity to buy such a set once and I'm still kicking myself for not doing so.