Yeah, I've heard these cylinders are a pain in the butt to bleed too. What is bench bleeding?
Bench bleeding is temporarily mounting the master cylinder by its flange in a vise, attaching a short length of tubing from the MC outlet, bent back to the reservoir. Add brakefluid, push the actuator rod a couple times and watch the fluid discharge from the tubing back into the reservoir. Replenish fluid as needed. You'll see the fluid kind of spit from the end of the tubing, and the first couple strokes will have some obvious air in the fluid. When you see 'solid' fluid, the MC is bench bled, and the tubing can be replaced by a plug to keep the fluid in the cylinder while it's being installed. The only thing left is to KEEP THE MC UPRIGHT WHILE IT'S BEING INSTALLED!!! Otherwise the fluid in the reservoir WILL spill, and you'll be pissed. I know I was!!
The whole process takes about 3 minutes and can happen directly before installation. One MC r/r I did, I 'benchbled' it after it was attached to the firewall, but before I attached the the brake tubing.