I'd recommend Urethane. I just did a set on my Ghia and was surprised at how easy the install went. The key (I think) was to clean everything and to install the bushings that rest in the torsion housing in first. I tapped them in with a small hammer and it made indexing my spring plates easier and the whole thing bolted together very quickly!
Also, be sure to use the lube that is provided so that they don't squeek.
