It's a simple bolt in deal. If you could afford I'd install new U bolts, so I'd could just cut/grind the old ones off. Your better with new U bolts, imo.
Here's a FF bar I installed in my 71. The dimples were in the frame but no holes. FF like what was mentioned, sends all the mounting hardware including self taping screws for the frame brackets.
BTW... someone mentioned I think about using through bolts and nuts for the frame brackets, I think. I don't think that would be a good idea, the brackets will be held in place much better with self tapping screws. Frame is too thin to reley on the clamping forces with through bolts to keep the holes in the frame from elongating.

Adding a rear swaybar is a easy worthwhile bolt in upgrade. Picture of my 71 with FF add on.



The spring perchs are moved in 3/4" on each side, not a problem with a stock width FF bar. You can see the angle in this picture, I think.