Just look at a 1969 1750 - which had a small rear bar. In fact, that's the best place for the parts - bar, clamps, links. The links connect to new bolts on the rear of the trailing arms that have an extended shaft for them. The only tricky part is the clamps for the bar against the body. Looking at the 1750 (anybody out there have a camera handy?) you can see where the clamps go. The bolts go right thru the body. Actually, the bolts come from the body out, adn the bushings and clamps fit over those, then the nuts.
But the bolts that are vertical come thru the floor in an area where the rear package shelf is doubled. I cut a 1 inch dia hole thru this so that I could get the bolt into the floor sheet metal, then covered that hole with a plug.