From the photos it looks very good though...
lots of rust under that?
Rust is not the main problem here (there is some, but not that extreme), it's more the incredible cobblework everywhere
Masses of filler are smeared around the back wheel arches, the paintwork looks not bad on the first view, but is an unoriginal tone and the paint-dust is everywhere (it was badly taped), and the cobblework at the technic is worst!
An electric fuel pump was mounted somewhere, where it doesn't belong, a cooling-water-pot of an Audi 50/Polo was screwed on the ventilator-box and connected with washingmachine-hoses, and the broken start-automatic was smashed off the carburator and replaced by a handmade (bicycle-bowden-cable, wood-screws, plastic-bag-zippers) manual choke. The handle of the choke was a lawnmower- or chainsaw-starter...
Although the K 70-prices increased slightly in the last years, for nearly 5000 EUR you can expect a real good, nearly mint-condition car (if one appears) - and not such a cobbled shitbox. O.k., the TÜV is still valid one year and the car shall be roadworthy - but this is not enough for that price.