RE: Power Steering Problem??
I had a problem like this a while back with my '79 Chevy El Camino.
It would fight me when turning and would squeal at "maximum Deviation" (the farthest it could go to either side)
The mechanic replaced the P/S pump, and when that didn't entirely fix the problem they tried to replace the Steering Gear Box. Sadly, my frame was too rusted for them to be able to put the new Gear Box on, so I don't even know if that would have worked....
I know this isn't much help, and I'm sorry. That is the only experiance I have with P/S.