Very nice looking rifle. . The basket weave checkering on a 1966 M88 left a lot to be desired for many old boys may explain why a 1966 was used over a per-64. Another thought is the stock on the M88 is quite weak at the magazine area if subjected to excessive stress I've seen a couple that were broken in that area. A pre-64 stock is very tough to find so why not do a custom stock?
The stock looks very well done, the finish, the cheek piece, the borderless checkering, from the picture, looks flawless apposed to Winchester Factory checkering of early 1960's. I like the full length stock and the cheekpiece is very well done.