I'm posting this as a data point in case the information might be helpful to anybody else. I've had a Gunnar Roadie travel bike for years. Good bike. Short brakes, 28 max tires. I wanted a more "all-rounder" with more capacity for dirt.
I like the result. Grand Bois 36 tires, Tektro long-reach brakes, and the whole thing went together as if someone smart had planned it, rather than as if someone not particularly smart took a few wild guesses and then threw parts at the project. The biggest hurdle was the fork, and I went with a Whisky because of a generous offer from a friend. I was glad to score lightly used 32-hole Pacenti rims on one of the lists, and those built easily. Bottom bracket finished up at about 263 or 264mm.
Thank you to those who offered help and parts.
~pb