Generally speaking, I suggest you avoid it.
There is no escaping the fact that equipment in poor condition tends to be less reliable than similar gear in good condition.
I’ve worked on plenty of rough pieces and warned owners about them. If you are thinking you’ve snagged a bargain because you’ve found the make and model you’ve been looking for in rough condition, think again.
Often, poor condition outside means poor condition inside, and poor maintenance in general. Corrosion is a good example. Once corrosion goes through equipment it can cause endless problems. Despite the best efforts of skilled repairers, these issues are not reversible. You cannot make a silk purse out of a sow’s ear, as they say!