Let's break it down chronologically.
I typed the letters up from copies of handwritten ones Jim wrote - 20 minutes on average for each letter (of which there are 55) - total of 18 hours.
Cory did the layout on his computer several times, because he'd get a draft done and send it to Jim for editing, and he'd have to redo the layout each time - 15 hours.
Cory designed maps of the area based on maps that a friend of Sally drew, based on maps that Jim drew - 8 hours.
Cory and I read through the whole thing to make sure we didn't miss anything, cross-referencing names for consistent spelling and other such things - 4 hours.
We went to Cory's work at night one night and printed and copied all of the pages - 2 hours.
I spent 4 minutes folding the pages (32 pages for each book, I think) into 9 signatures, 5 minutes poking holes down each crease in each signature, about 30 minutes sewing the signatures together - 19.5 hours.
I glued the edges of the pages together (where I sewed), glued the spines on, and glued the covers on - 10 hours.
Lastly I taped the spines with black duct tape (it looks better than it sounds) to reinforce them and make them a little more interesting - 2 hours.
So the total hours we spent on the project (not including the times that we sent edits to Jim and waited for a week or two to get them back and that sort of thing) is 68.5. I started typing (not earnestly though) in January, and we got three groups of letters throughout the spring and into the summer. And I started binding I think at the beginning of July or the end of June.