Great advice except one thing. When you say "the sprag fails the tailshaft spins at an uncontrollable speed." that's not exactly true. When something in the driveline breaks, the tailshaft may spin up and damage the sprag/roller but when the sprag/roller fails the tailshaft becomes the held member in the planetary set while the front drum becomes the output member spinning at 2.2-2.45 times the engine speed.

440..guy, another thing to note. Aluminum drum is not a good choice for street. They do wear considerably more than a steel or steel jacketed drum requiring more frequent band adjustments and fluid changes.