FWIW, we worked up a spreadsheet with the hp requirements at speed for a stock rcsb silverado's aero cd. It would require 1030hp to overcome aero at 220mph, plus rolling resistance, which could add up to 1200hp or so.

Parish, with the right gears, you're ready for 220+... but I suspect a few runs at 220mph would show the strength of the 4l80e 4th clutches