I am only guessing, but I doubt that your "beater" W116 has approached the point of being unsafe (can't tell without pix of the suspension areas). In my mind it has passed the point of being unsightly. If you want to try return it to having a semblance of its intended beauty with some expensive bodywork, it would be a fool's errand, IMO. Better to put money in another car if you want something that will end up looking good or last more than 5-10 years.
If you still want a W116, they can still be found in great condition for little money generally out west or in Texas. They may have mechanical issues (like "no reverse"
) that need to be addressed, but those are a lot more curable than cancer.
Rick