This is a very basic model built to low workmanship standards. The stay and blade ends are crimped onto stamped dropouts. There's very little penetration of the brazing medium between the seat tube and seat lug. 25.8mm seat post suggest hi-tensile steel, assuming imperial tubing. The rear derailleur is the bottom of the line Hurer Eco. I'm really surpised to see tubulars. There is massive frame clearance. The Weinmann 730 aren't short reach brakes, so I'm wondering if the tubulars are a retrofit, though the rims look they could be period correct. Too many photos for an assist. OPs's photo's here : https://www.bikeforums.net/g/album/18215949