A friend of mine did the center-pulley-PS pump thing and before too long the water pump gave up the ghost. I'd advise using the best belts you can find, and pay close attention to the belt tension if you take this route.

Possibly a better way:
I read a great post a couple months ago where someone had remounted their PS pump forward just enough to run that pulley off the pulley intended to drive the AC pulley. NOT an IPD kit. PS pump changed at '85; yours should be the same as the '87 below. See quote below.

Thread: http://www.brickboard.com/RWD/index.htm?id=958505
In addition to the neat solution below, the thread discusses some of the hazards of the various methods of using the center pulley to run the PS. Basically, it's not good for the alt or the water pump.

Quoted from above thread:
Yes, I assisted a friend in performing this modification to his '87 240 Sedan. We were able to accomplish the task by moving the Power Steering pump forwards on the mounts using new bolts, threaded rod, nuts, and washers (and some cut tube stock in places where many washers were required). We effectively bypassed the AC compressor and did not have to disrupt the two Alternator/Water-Pump belts. However, I would strongly suggest changing at least two of the Power Steering Pump rubber bushing mounts to IPD Polyurethane Bushings (there are 3 total if you decide to do them all). If you leave the stock rubber bushings in place, the Power Steering pump will move enough to shift it's pulley off-axis from the crankshaft pulley. I'll take pictures and post a step-by-step procedure at some point.

Also, I would advise changing the Alternator rubber bushing on the adjustment arm that attaches to the engine block. Switching this bushing to a Poly bushing from IPD will help bring your alternator back in line and reduce belt noise and drag on the engine. By leaving the other two bushings as rubber, you allow some of the vibrations and sudden torque/amp loads to be dissipated by the rubber.

[Poly bushings can be had from fcpgroton.com - Sven's Maintainer]
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[aka Sophie's Maintainer] Sven: '89 245, IPD sways, E-fan conversion, 28+ mpg - auto tranny. 850 mi/week commute.