Can't you use a Campy long cage rear? Velomine has a nice selection of very affordable wheels with Campy compatible hubs. Whatever you do good luck. That is a really nice bike.
A 32t on a campy long cage would be iffy. I've heard a few accounts of people claiming to have made it work, but Campagnolo cassettes max out at 30t sizes and 3rd party versions that are bigger are few and far between not to mention expensive from what I recall. I wanted as close to a 1:1 low gear as I could manage for some of the steep rollers we have around (yes they can be found in N. Texas, and the guy who coordinates our gravel rides often goes looking for them. Not steep enough to need a 1:1 if I was on a road bike, but with the gravel you really can't stand and mash a gear so sitting and spinning a really low cog is the best bet. The shift-mate isn't perfect, but it's about as good of a solution as I was able to find when I did this build.