My story much the same on my 53 1/2 ton with a 4.11 axle ratio. I found a stock bore 261 and had it machined .030 over and polished up the crank then I assembled it with new insert mains and rods bearings, Best neoprene rear main. Around the same time installed an okie bushing replaced axle bearings and seals and found NOS pinion bearings and carrier bearings. Next I purchased a Mother Trucker 3.55 ring and pinion. Set it all up in the garage ,which went really smoothly, there are some good articles on the stovebolt on this.
Bottom line is now I have an engine with more power, taller gears and taller tires and I can easily cruise with the traffic on the freeway.
Jerry is right you know, before that, the engine just seemed to be over revving but it is not, with stock gears it is operating out of the sweet spot though at anything above 50-55 mph.
1953 Chevrolet 3100 261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done In the DITY Gallery Video of the 261 running
1964 GMC 1000 305 Big Block V6, sm420, the next cab off restoration
