You can, I believe, still buy it through his store that he had a relative running for him. A lot of the stuff (spinning wheel parts, etc..) are unfortunately unavailable forever at this point but I think the books are print on demand:
The hide glue book is decent, but there was imho a limited amount of information you can write about hide glue (if i was doing more esoteric restorations it would have undoubtedly been more useful).
The Compleat Early Nineteenth Century Woodworker is a useful and interesting book. I have a rather extensive library so it duplicated a lot of other information I had already but its still and excellent book nevertheless.
The book on Shellac, Linseed Oil, & Paint is without a doubt his magnum opus, if I had to pick one of the three this would be it. I definitely learned quite a few things in there that I haven't found anywhere else.
If you're interested in such things his Spinning Wheel Repair book is also quite useful, its small but I picked up a couple of handy tips that stood me well for fixing a couple of problem wheels.