Installing the 3.55 rear wasn't worth it for me, but only because I didn't do my homework. I changed too many things at the same time. First off, I changed from a really tall (7.50x16) tire to a much shorter low profile tire to get the truck to sit lower. Net gain: nothing, in fact maybe even more RPM at cruising speed. Only after changing to an overdrive transmission and later 3.90 open rear did I get down to a comfortable cruising RPM - about 1900 RPM at 60 MPH.
Granted, with a stock Stovebolt a 15% reduction in RPM is better than nothing. You will be turning 2600 RPM instead of 3000 at the same highway speed. My experience, though, is that you need a more dramatic reduction in RPM to really be in the comfort zone of these old long stroke motors. When you get into building a more high performance engine with better breathing and more cam, the whole equation starts changing again, and you have to be aware of where your torque peak is and what gearing you need to optimize response at any given road speed. So to answer your question - it's a qualified "yes" but, plan ahead.
