I can't speak about the Espree in particular, but I did pretty much what you're looking to do with a 1984 Del Rey. It fits 650x38 tires with fenders no problem. I could even get 700x38 to fit (sans fenders), but clearance is tight at the chainstays. Brakes are Tektro R559s and they are maxed out with the 650b wheels. You might need to measure to make sure they would fit the Espree.

I will say though, I don't love how that bike handles a front load. I have a bag that attaches to the handlebar with a Klickfix mount, and that makes the steering feel pretty heavy. It's doable, but steering feels like a chore on longer rides. I don't know the numbers but I would assume it has fairly high trail, and I imagine the Espree would be similar. It's not a dealbreaker, but it might be something to consider.