I got a set of new calipers to put on my '82 XJ750 and I was wondering if there was anything I should watch out for that the Haynes manual doesn't mention. I'm going to stick with the original rubber brake lines for now.

Should be a pretty easy job. I like to scratch up the banjo bolts and crush washers with some sandpaper to both get any residue off them and create a good sealing surface. I've had little leaks develope around the banjo bolts before, a little light sanding stops it.

But replacing the calipers is a pretty straight forward job you shouldn't have any problems.

If the washers on the banjo bolts are copper, you can anneal them by placing them on a brick and heating them with a propane torch, and they will be re-usable. But if the caliper comes with new ones I would certainly use those.
Jim