But for the lack of jig holes in the back, my knee-jerk answer is Roper. I suspect your knee-jerk answer might well be the same. That said, I have a dim recollection of hearing some (real ones) didn't have such holes. I'll see if I have any notes/obscure articles or anything else to confirm that.
If Roper's, the wood is better than normal---as is what appears to be the inlays. That doesn't scare me off, because I have a (very) fancy pair of thumb-rest targets that are for damn sure Roper's---very fancy for Roper's anyway.
Ralph Tremaine
Well, that didn't take long---truly amazing what a little organization will accomplish. As close as I come to confirming some Roper's don't have jig holes is "almost without exception" they do have them. The "Gagne Fingertip Ribbons" on both sides identify these as ambidextrous grips in "Roperdom" (sometimes----my thumb-rest targets have the ribbons on both sides too---and ambidextrous they are not). Given a palm swell on one or both sides (not shown), the diamonds, and a slight swell at the bottom (also not shown), they're Roper's. Given they have no jig holes, they're not----"almost without exception". If you want them to be Roper's---with no arguments, fashion an appropriate punch for jig holes (about two inches apart---more or less centered, side to side, and top to bottom), and Voila!! If that would make your teeth hurt a bit (as it would mine), Griffin & Howe is my next (and last) choice. So far, everything I can see---no jig holes, the inlays, the checkering and the finish (original??) says G&H. (And it's not so much that the finish says G&H, as it is it doesn't say Roper.) Both Roper and Griffin & Howe are at the top of the custom grips heap for the period. Whatever they are, they're right up there on the spiffy scale!!