I would think the bars could be shortened, 29" is plenty long for the bottom bar. You could mock everything up with some square tubing substituted for the bars. When you figure your lengths, shorten the top and bottom by the same percentage of their total length. IE, 10% shorter would mean 2.9" off the bottom and 1.7" off the top.... On narrow framed cars with triangulated 4 bars, I've mounted the top bar brackets as much as half way up the center section. When all else fails, you could switch to a parallel four bar with a Watt's linkage, I'd have to be really desperate for space before I went with a panhard bar for a street car, though. They work fine on a drag car, but that's about the only time I'll use a panhard bar.... I just don't like the way the load the suspension on cornering....