Can't get fluid from master cylinder

I'm trying to bleed the power brakes on a 67 mustang. I can't get the fluid to come out of the Master cylinder. It is a new unit-booster & M/C. I disconnected the brake lines from the M/C and pumped the brakes but no fluid flow. No there is not a cap or plug in the holes. I had someone push on the brake pedal and it does travel what should be normal travel distance. I also disconnected the pedal to ensure the rod was travling the full stroke. When I look into the M/C and have someone push on the pedal I can see the piston move but it looks like it only moves 1/16 - 1/8 inch. I don't know what is normal. There is a plug on the bottom that the book says is a piston stop?? Any Ideas?

This is not my car,I am just working on it for a friend. He said that he bought the brake booster/master cylinder from Checkers auto over 2 years ago. It didnt have any fittings to bench bleed it. I will give the 2 finger trick a try. It doesnt appear to have an adjustable rod and he doesn't have a manual just an old cheap book that just touches on the brakes-nothing in detail.