I've got the hack and the bike - looking for tips or examples of installing a Puch 560 to a pressed frame bike like my Puch 250  -   -   -

Hi Phil,
sturdy as it might be, there's nowhere on the Puch 250's spine frame that's in the right place to hang a chair on.
You'll need to make a subframe to go between the Puch's engine mount bolts or other suitable strongpoints and where the sidecar's mounting brackets have to attach.
To see where these are type Velorex USA into your search engine and search the site for attachment instructions.
I build subframes from flat plate and square tube because it's far easier to make tight fitting welding joints in that material than it is to make them in pipe or mechanical tube.
You will need access to and the requisite skills (or friends who have same) to operate a welding machine, a drill press and a chopsaw. From my own experience, the second one builds real easy.
Fred Hill, S'toon.