Art:

I haven't found a need to bench bleed.

1. Install the MC and fill with fluid. Wait till bubbling stops.
2. Pump the brake pedal. Probably drops to floor indicating air trapped.
3. Crack open lines. Depress pedal and block in down position with something eg.2X4
4. Tighten lines. Release pedal.
5. Repeat from 2. until pedal firms up. Then proceed to 6.
6. Bleed brakes if you want to.

I park facing up-slope, so that air moves to MC exits. There is some brake fluid spill that's easily wiped/washed away.

"If you don't you will force air into the lines and need to bleed the entire system."
Since the bleeder screws are kept closed, air will be forced out the end of the MC exits (air rises to the highest point which will be MC).
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1980 245 Canadian B21A with SU carb and M46 trans