How Problematic is Rust?

I'm thinking about doing bastard packs on my 91 XJ, but the only thing I fear is the rust, there is a lot of it. I would assume that I will break most of the bolts I try to remove, but how much of a problem is this. If I do break a lot of bolts can I get them out and replace them, or is this lift a lost cause? Any suggestions are welcome.

Do the lift. Use lots of PB blaster and some heat, it will probably take longer than others. Make sure you have airtools.