Hmm.. Well I've got a brand new bridge high gain in front of me and this looks just like it on the bottom. I'd say it's one of those with one of the later V63 surrounds. Definitely a good deal though since the surrounds are unavailable. I'd be interested in buying the surround if it's for sale when you get it Andrew.
I would have actually bought it to reshape into the '67-'68 style as the shape is not correct for any actual vintage RIC but provides enough material to make it correct.
I think it is correct for a '63. We have gone down this road before, but Scott Jennings did verify that the black and white photo of the '63 4001 in the Smith book, that Scott had for a while, is indeed orginal and they look virtually the same.