Our team is the same weight. For tires, I’d recommend 50mm tires at 50psi for most dirt roads. 60mm at 40psi covers unmaintained roads, muddy roads, or ones with huge gravel. I’m a big fan of the Panaracer Gravelking series in all its flavors. You do have to watch the tire’s sidewall pressure rating. We’ve had tires blow off at 5psi over the rating. Schwalbe and Panaracer tend to have pretty high pressure ratings for the size, so they’re a good bet.
I’ve heard those Cannondales can fit 650b x 47ish tires comfortably. I’m not sure about the largest 700c tire.