I don't know if this will work for you or not but you could try it.I replaced mc and brake booster on my 67chevelle a few years ago and played hell trying to bleed the brakes had helper pump brakes, would not build pressure and pedal was way low. I tried the vacumn bleeder pulling fluid through the bleeder. I finally called mp brakes and the rep told me to gravity bleed them. So I started at the rt rear filled mc to the top and loosened bleeder then left it for about 5 or 10 min and watched fluid level until it was down about a1/4 inch then went to the rr,rf and of. I then got in and brakes were excellent. This worked great don't need a helper either.