I have also encountered direct comparisons to the mid-sized 1959 neck shape.
A great Joe Ganzler quote from the LPF, 1-15-2004: "I will still also concede that some of THE best Les Pauls I've ever heard and played were '68's that have been routed for 'buckers!      Honduran Mahogany as stated in the flyer released in 1968. This is what is commonly seen as one of the primary differences between a 50's Les Paul and a 1968 Les Paul. These have been x-rayed and confirmed to be IDENTICAL to 50's bumble bee caps in every way. 68's are early 69's use 50's wiring, with the caps moving to a different lug on the tone pots thereafter. I would say they are generally very similar to a 50's carve except that a DEEP dish carve is much less common, with a slightly less deep edge the norm. Les Paul's made after the mid 70's have a rounded bottom on their tenons to facilitate a wider acceptable tolerance in construction.