Sachs=Solid. Good deal
The engines are German and most of the controls are the standard Magura and C.E.V. so parts are easy. I'd say the engines are very similar to Puch but not as many performance parts available . The Sachs 505 series engines are among the most elegantly designed imho.
Your first order of business will be to read the plate attached just above the flywheel cover. it should say 505 or 504 followed by 1 (for single speed) then a letter. D=30mph A=25mph B=20mph C=25 (the "c" version is not very common and is just an "a" with a "d" jug on it and is no more powerful than an "a")
mijunkin is right, it looks like a pinto frame and tank with a Sachs engine and covers,. Pintos didin't sell real well and I wonder if there was a warehouse full of Pinto frames somewhere and Sachs just bought them and welded new mounts to them? The good news is it would make it much lighter than the typical Sachs. Cool looking bike at that! Get it up and tunning and it will become the bike you ride when waiting on parts for your others.