Mine weighs about 6000, and I get about 70 MPH out of 3000 RPM.
Ratio seems good all around, but not as good as more gears would be.
I would be inclined to ditch the TH350 unless it is seriously built.
Every time I drive on pavement, I try to shift to a higher gear that I don't have.
http://www.cartestsoftware.com/cartest2000/index.html
If you download and install the demo, this is a pretty good little program for figuring your performance with various engines, gears, weights, wheels, etc.
If you input is accurate, the results are pretty spot on.
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68 Chevrolet k20 Longbed 350 SM465/205, Dana 44, 14bolt, Power steering, Power Disk Brakes, 35" BFGs.
84 Chevrolet Suburban K20 6.2 Banks turbo TH400/NP208 Now with G80
68 GMC C20 Parts? Truck
And a few cars
