I have to add an additional Info:

I now remember that I had created the raw (unsigned) transaction not with Electrum 1.7.x but with "https://coinb.in/#newTransaction" - and then I signed with Electrum 1.7.x on my old offline Linux PC (with equally old Linux version)!

So do I understand correctly that here - in the ray RX already - the "non-standard stuff" was created leading to "scriptsig-not-pushonly" error?

Any ideas what I can do (maybe via advanced settings there?) to get a workable raw TX?