Fred it is the 33's that are causing the problem. Check the advertised pressure to see if there is a difference before installing a different master cylinder.
In order to get 165 ft. stopping power back again you may have to upgrade the complete system.
The taller the tire is the more hydrolic pressure it will take to press the discs/shoes into the rotors/drums.
And the more pressure used the quicker the steel will wear out.
I'm thinking a couple of grand for a complete new system would be needed to get them 33's to stop as desired.
Others may prove me wrong.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />