Erik,
Just me talking here, but 3.73 gears really won't be that much of a jump. With the 4 speed you could go a bit higher and still have the low gear to get rolling. A few years back I put a 3.07 rear end from a '70(still 6 lug) in an a '64 I had. It had the 230 six with the 3 speed, it pulled just fine and after a few carburetor adjustments I was getting 17-18 mpg. It would cruise along all day at 65-70 mph with no problem. Of course, I was not pulling anything with it on a regular basis either. I did haul another truck with it on a 16ft trailer a couple of times, but as long as I let it take it's time it was no problem.
Like I said, this is just my opinion. I have always liked taller gears but that's just me. I'm sure others have their preferences as well.
