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With your rear gears and and the small mechanical roller your new 482 won't like 5th gear (0.64) at any reasonable cruise speed. See what kind a deal you can get from Brent on a TKO600 with a 0.82 overdrive. Summit sells them for $2195, for a reference point.

The TKO 600 has a 2.87 first, compared to your TR3550's 3.27. You will appreciate that with more cubes (482) and the 3.31s. First gear will be much more usable. BTW, don't go 10 spline input (weaker shaft) go 26 spline. You'll just need to specify 26 spline when you order your clutch disc.

You're one of the few lucky ones that got a 31 spline Currie crate rear, most were 28 spline. As you said, you'll be fine with that.