I have a 'Bendix' brand one, but it's probably 35 years old. I'll poke around and see what's out there now, but Dennis has already listed some good suggestions.
The key point to remember is that the brake fluid is pressurized at the master cylinder location. You need to be careful when hooking it up, and especially removing it to not blow brake fluid all over the place. Still, it's the only thing that worked on those cars,(and many in the past). I have an old 'Vacula' system that hooks to the bleeder screws at each wheel, to vacuum draw the fluid from the master cylinder, and the majority of the time it works great at bleeding/flushing the system. When that doesn't work, I break out the pressure bleeder.
I also have a set of high pressure gauges that attach at the front/rear bleeder location with adapters. That is how I can tell, with verifiable data, that the pressure bleeder makes a difference in system pressure, at the brake locations.
FWIW, you're not likely to get better brake pressures with your 'manual' brake system, as opposed to a vacuum booster & a 'Leeds' type vacuum pump, even playing around with different master cyl. piston bore sizes. I called Baer & Wilwood at the time also, regarding master cylinder bore sizes, etc. Bottom line, the typical answer you'll get from them guys is you need at least 18inHg of vacuum for the booster to work, and you have 12.
When I converted to 4 wheel disc on both cars, I went thru all this. Bottom line, added the Leeds pump to both cars, retained the factory vacuum booster, and great pressures at the wheel locations, that were NOT attainable no matter how hard I pressed the pedal in the car.
Oh, my Monte originally had a hydroboost setup on it, but I hated how it looked, so it was replaced.