I ended up with a Bianchi Brava frame; it has some rust issues, but they can be fixed, i think. While it looks very steep-angled, it has a surprisingly long wheelbase (41.5"), and has brazed-on studs on the front fork and the seat stays; I imagine they are for mounting front and rear racks. Has anyone used one of these as a touring bike?
(It isn't a question of Gruppo or wheels; there aren't any. It would be a frame-up build.)
I'd work back from your load and the size of tires optimum for carrying it. If that's upwards of 32mm and the frame can't take anything bigger than 28mm it's a limit. So the frame may, or maybe not work.