First off its a Wells Index, its probably an 847 if its factory, the iron is worth it alone. I have no idea if its factory, but Monday morning give Rick Robeson a call at Wells Index, if it was a factory conversion, you will have absolutely 100% no worries of support.
Go over to the practical machinist board and do a search for Rick Robeson and you will know why. I've got a '78 Wells Index cnc from the factory. She doesn't get much use anymore, but she still gets used, and I've never had such fantastic support from any company anywhere, ever.
If its not a factory wells index conversion, I'd think really hard about it. I don't think its a bad deal, I don't think its a great deal, but if its not working and not a factory conversion, I'd probably skip. If it is a factory conversion (and over the years they have used quite a few different controllers) there is a company that will support you, and support you well.
Wells Index is still really good iron.