I have done everything I can think of to resolve this power steering screeching/squeeling problem.  I cleaned and roughed up the pullies, deglazed the belt but the noise continues.  I sprayed the belt with water while the engine was running which did not effect the noise.  I tried loosening and tightening the belt. The noise is almost like a grinding sound.  I am starting to wonder whether the noise could be coming from the pump bearing or something else inside the pump.  Has anyone else experienced a screeching or squeeling power steering pump?  Any suggestions on how to diagnose the problem as coming from the pump before I spend a bunch of money on a pump rebuild (which may or may not solve the problem)?  This is an original Eaton Pump.

On my power steering setup, an Eaton pump, I'm using an AX profile belt. A = 0.5 inch (13mm) depth is 8mm. As Kultulz points out if the belt is too narrow it may be too deep into the pulley. 
On the other accessories I'm using 2 of ZX profile. Z = 3/8 inch ( 10mm ) depth 6mm. X being cogged/toothed.
Don't know if the ZX  AX notation is a UK thing or you use the same.    
Good  luck.
stuey

I sprayed the belt with water while the engine was running which did not effect the noise.  I tried loosening and tightening the belt. The noise is almost like a grinding sound. 

The spritzing determined if it was the belt and/or pulley. You need to remove the belt entirely and run. If the noise is gone, it is the pump.

Turn the pump pulley by hand (w/o belt) and see if you feel any roughness/resistance.

When you went with the 292, did you keep the 256 damper/pulley?

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Yes, I used the 256 crank pulley and the bolt-on cast iron power steering pulley.  When I turn the pump pulley by hand there is some resistance but I don't feel any roughness.