Thanks Tom! The repro one I have fits...a tad oversize in a couple spots which gives me something to work with. The bottom of it is flat, and uniform thickness top to bottom. My stock has a slight curve from top to toe, just like your's shows in the 4th picture. So my question was should I heat and bend the buttplate to fit the curve, or file off the curve of the stock flat. Your pic answers the question - neither! The thickness of the buttplate needs to taper towards the toe. I think my repro with some tender love grinding the right profile on it's underside will work just fine and look great in the end.
Thanks again!

Now I just need to wait on a magazine plug. I suppose I could fit everything and wait, or find a friend with a lathe to make one. They seem easy enough to make. Classic Old West Arms has norinco ones, but with metric threads, for $35 +$16 for the screw. I'm not desperate enough to swallow that one times 3 just yet.