Ok, so your car is a female (lol?) It is odd to have brake fluid leaking as described, but leaks can be obnoxiously tricky to nail exactingly, as fluids like to leach and seep around to places that would mislead you into thinking the origin of a leak could be somewhere it is not. When these problems strike here, I use a ridiculously bright million candlepower LED spotlight, magnifying mirrors, clean dry rags, and a person in the vehicle to actuate the braking. I insist on clearly seeing a leak in motion repetitiously to be certain of where its true origin is. Brake fluid really can play some games with you almost more than other fluids. You definitely have the problem isolated, but could it be as simple as loosening and retightening the brake lines a few times to establish a good seat / seal at these connection points? If I understand correctly, you are experiencing leakage without any actuation - literally a gravity based leak. If I was there, I would leave everything connected (brake lines) but unbolt the MC from the face of the brake assist unit and coax it forward a couple of inches. With it just sitting there all by itself, the clean dry rag, ultra bright light, and magnifying mirrors ought to nail exactly where the fluid is emanating from, then correct as needed.
As far as the hydroboost? It has the same stroke as a vacuum booster, so no weirdness there. I could be wrong, though it sounds like you may have a problem of having one of our short MC pushrod models, where the tip of the MC pushrod sits well below the MC mounting surface, but interfacing with a deep / early GM pushrod style hole in the back of the MC. This isn't going to cause the brake fluid leak, but you need to install the spacer bullet / slug / plug into the backside of the master cylinder. Alternately, if you have our model with the MC pushrod that protrudes out a good 1 1/4" +/-, then you would not use any spacer bullet. You have to get this right. If you by chance want to do a quick check to see where you are at for MC pushrod clearances, you can put a dab of white lithium grease on the tip of the MC pushrod and then place the MC up against the brake unit. If all is in basic range, it should leave some witness / grease transfer to the MC piston. We have pulled back our MC pushrod lengths a few thousandths over the years, as we would rather have an air gap between the pushrod and the MC pistons as opposed to the opposite where the MC pistons aren't being allowed a full state of release against the snap ring in to the back of the MC (leading to dragging brakes). You are not going to feel a .020 - .030 air gap in the brake pedal response, but you will certainly notice hot dragging brakes if the MC pistons are preloaded. Also, contrary to some misinformation out on the internet, note that the adjustable brake pedal pushrod under the dash has nothing what so ever to do with MC pushrod to MC piston clearances. This adjustment under the dash is only for the purpose of setting the brake pedal height to suit your particular tastes.
Overall, I'm sure Baer will or already has you covered as needed. I know it's frustrating, but you are almost there. Stay patient and clear headed, and stop pulling your hair out (!)
Do let us know what you ultimately find, as so many of these forum posts never wrap up with what the actual problem was found to be and the remedy that solved for it.
