I agree with most of the others, it's probably not going to have the clearances for the wide tires and might not take fenders at all, without some gymnastics. But serious brevets are ridden on a wide range fo machines, not just Herses or clones of same.

I'd first pop in a set of wheels and see how wide a tire you could fit. Look at lateral clearance as well as radial. The tire needs about 8 mm clearance to the fender, and maybe 8 mm laterally to the fork blades and other frame members. Also look at the brake reach requirement. Short-reach brakes aren't usually able to handle 28 mm tires with fenders.

Since the fork is off of the bike, you can do a precise measurement of offset and of the frame angles, to compute trail. That will tell you if you can carry a front bag conveniently. The FB is not a requirement, just a style a lot of folks like.

If your wheels can handle a 11 tooth cassette, you can get a super wide range with only two chainrings, saving weight.