When the LSPV in my '84 xtracab failed massively I removed it and spliced that line to the rear brakes. Then I removed the return line and capped the connection at the junction block on the frame rail by the front passenger wheel opening. My braking improved dramatically. I also had V6, four pot calipers and a late model master cylinder. When the four piston calipers are properly set up they are awesome!

I had a constant load of about 300 - 400lbs in my bed so full brake force at the rears was never a problem, even on icy roads.

I just wish I could get my '89 4runner to brake like that, but first I have to deal with engine problems that are causing low vacuum, which I believe is not enough for my brake booster.