[MetalMan]

The Slipperential uses the Revo slipper clutch, so yes, the 36t spur works.

If you were to use the buggy diffs (43/13) as opposed to the truggy diffs (43/10), you would have a gear ratio closer to what you are looking for.

With the Slipperential (44/20), buggy diffs (43/13), 36/20 spur/pinion, 6" tall tires (to account for ballooning), and 35,000 RPM, you'd be looking at ~47mph. If you were to factor in 5.5" tall tires that won't balloon, you're still at ~43mph. Dropping down to 30,000 RPM with 5.5" tires would give ~37mph, which in many cases is a good top speed (might even be too fast for some tracks). So it looks like gearing wouldn't be too difficult.