Moparnut,
It's summer time and cruising time. Pull the driveshaft, linkage and shifter, unbolt the tranny, then drop it.
Open the side cover and fix the problem, then reinstall it. If you want to put in the OD, use the new bell. It can all be done in a couple of hours.
During winter time, put all of your new stuff in at once. If you cut your old bell, you can't use it with a stock tranny anymore unless you change stuff around.
Rob