Hi Ross,
Not to butt in but a 235 and 3.55 rear gears generally is a good combination. I have 3.07 gears and mine works. As Sweet said hills can make me drop back to 4th, but usually I don't have to. 3.07/3.08 is the leanest edge of things I'd suggest, however. I'll explain a bit more...
If you had bought a 1960 Chevy El Camino with a 235 and a three speed with overdrive, you'd have gotten a 3.70 rear end. That's how they came from the factory. Overdrive would reduce the rear end gear by 30%, bringing it down to 2.59. It would have had smaller tires/wheels but with 3.55 you'll still be better off than that El Camino in overdrive. A big old station wagon would have given you the same rear end ratio. My final drive ratio in the pickup with a fifth gear of .86 and a rear of 3.07 is 2.64, so I'm right where the El Camino would have been...a little better, really. On the other hand if you had bought that El Camino with a 3 speed without overdrive, your rear end would have been...3.55. So in any case it will work for you. Good luck!
