Unless you really care about original looks, swapping the reservoir is probably the easiest way to be able to use the pressure bleeder. Most of the original three-cap ones are in pretty crappy shape by this point anyway.
I've never bench bled a new MC and never had any trouble.
If you look at the MC you'll see why you don't have to: the outlet ports that come out the side are at the top of the cylinder. So they will bleed by themselves if you do the job properly.
Install the MC in the car and thread the brake line fittings but keep them loose. Then fill the reservoir. Fluid will come out of the bottom front port first, once that happens tighten up the fitting. Then wait for fluid to come out out the other ports and when it does tighten those up as well. Boom, your MC is full, then just bleed normally at the wheels.