All right fellas, here is the update with pictures as promised.
The description offered by 63sbssbbw is right on the money and well stated. The rear cab mounts are the same. They bolt straight up with one difference, the 63 cab used a 1/2 x 5 inch bolt. The 62 cab uses a 7/16 x 5 inch bolt. Mounts are the same, just one size skinnier on the bolt itself.
The front mounts are where the difference lies...
Drop the mount bolt through the floorboard...
Climb underneath and here is what you will see...
My floorpans aren't quite rusty enough that I am going to change them. I just plan on cleaning them, etching them, and POR15 them. So, I will re-drill the mount holes inboard as needed to line up with the frame mounts of the 63 frame. It also looks like I will have to build a shim about 3/8 inch thick to space the front of the cab up to level the nose of the cab.
The second part of the deal, which I haven't exactly decided which route to take is the master cylinder. The 63 cab used a normal master cylinder bolt pattern with two horizontal bolts...
The 62 cab has the dual hole deal, and does not allow a later model 2 bolt master cylinder to bolt on.
I think I will wind up shaving this part of the firewall smooth, then installing the underdash brace out of the 63 and drill the needed holes in the now shaved firewall. This will allow me to run a later model disc brake master cylinder.