You’ll have no trouble with
You’ll have no trouble with the rear wheel in the dropouts going from 126 to 130mm with a steel frame, that’s a bend of 2mm per side. My ‘cross bike has frame spacing of 132.5 so either road or mtb hubs can be used. I cold-set a steel frame after a crash easily 20mm by hand. Also, the if you get STI there is an adaptor to go over the braze on for the downtube shifters, I have this arrangement on my commuter.