It really depends on how much work you want. Any way it goes I would recomed taking the tub off. You can cut the rear off and reweld it but it's gonna need braced and you need to make sure it's square. You can also have it patched but that could turn into a nightmare. You need solid metal for a patch so they may end up cutting out way more than you thought to just try to patch it and then you still just have a patched together frame.
Changing the fram would be your best bet really and you could do a good por 15 or powder coat on the new frame after it has been media blased or whatever.
A lot of work anyway it goes. Thats why when I looked for my yj I was careful.