Why not swap your R&P's for some 4.625's. This would give 1.4x4.625=6.475 and (33/27)x5.125=6.264 So there is not a lot of difference in high range between the Sammy case, 4.6's with 33" tires and stock tires, stock t-case and 5.12's. The small difference is actually a good thing as these numbers are always theoretical and in the real world the rotational mass of the larger tire and the wind resistance it creates will actually require a bit more gearing than the calculations show.