Sounds to me like you want to remove the the parking brake drum, backing plate, assembly, etc. Given that the brake drum fits on the rear output of the t-case much like a yoke fits on the pinion, I don't believe you'll pick up ANY extra length by removing and replacing with a normal yoke. I do believe however that the drum shaft OD and the spline count is the same as a pinion tho, so you could at least drop a few # of weight there. Any additional length changes would require an outputshaft modification - shorten, machine down for new locking nut, new seal, possible new rear bearing, etc....more $$ than it's worth.
You'll pick up 3.5" of wheelbase reversing the rear leaf packs. That's the normal change for added driveline needs.