[mongocanfly]

The hydroboost has no effect on which wheels stop when mashing the pedal... sounds like maybe your master is bad...have you tried bleeding rear brakes? Also on the proportioning valve, it has the trip feature, meaning the internal spool can trip and send all the fluid to front or back....check and make sure it isn't tripped..mine was one time and all I had was rear brakes.. they make a tool to screw into it to hold the spool centered so you can bleed the system..
Another thing to check is the condition of the rubber hoses, If they're orig,it's probably best to put new ones on,
At the least it sounds like your system needs flushed..