What transmission do you plan on using? I have a '50 3100 which came with a Saginaw three speed and a 3.08 six lug rear axle, and 28" high tires (stock).
The truck could not get out of its own way in first gear. It did go down the highway at 65 MPH without the engine screaming. However, each upshift began with excessive lugging, required revving it up excessively prior to the next upshift in an attempt to reduce the lugging upon the next upshift.
I couldn't live like that so I swapped in a T-5 from an early 80s S-10. It has .72 overdrive. You can run some pretty steep rear end gears with that 5th gear ratio. I used a 2001 Nissan Xterra 6 lug axle with 4.64 ratio and limited slip. It was a dream to install in the truck. Right width, 1950 rims bolt on, easy to adapt parking brake. This rear axle is basically a Dana rear axle. I went with 30.5" tires to dial the setup in. The 28" tires made 1st gear a granny gear which was not of much use. The 30" tires make first gear act like first gear now.
I can pull stumps and drag them down the road at 70 MPH.
