Swaping from small to LARGE glass. How would you do it?

[Putter]

Okay, please don't just blurt out "Swap the cab".....

My '69 (grandpa's truck) was a big rear window (naturally). After finding TONS of rust in the rockers, corners, and across the windshield (he added cab lights), I located a '68 small window cab is great shape. 95% rust free, and minor dents.
Swapped them out years ago. But now I want to go back to the full size back glass.
Is there a GOOD way to just swap out the rear of the cab? I know it has outer/inner skin, but is there a suggested process? Like, cut here on one....here on the other. Brace here....weld here....blah blah blah.
And I am not looking for hard-core-step-by-step planning, but a general idea.

Heck, is it even possible?

If I can't do it that way, I will be forced to (a) find a big window board member to swap with, or (b) just put a 67-68 front clip on it and roll.


Anyway, suggestions needed & welcomed.