72 4x4 poor front braking

[Chris183]

I'm having trouble with my front brakes they don't want to lock up on a hard stop. The backs have no problem. I was able to force the proportion valve to trip and reset so I think that's good. When I checked the front hydraulic pressure the most I can get is 800 psi. at the caliper and master cylinder. Is this normal or on the low side. I got the same after bench bleeding the master cylinder and lines. Does anyone have any thoughts?
Thanks Chris