Has anybody converted an 84Rx7 GS to power steering? Will parts from an 85 work? Are there any out there after the cash for clunkers rush?

 

Here's my 2 cents:
1) The steering gear boxes for manual and power steering are different. If you use Mazda parts for a 1st gen, you'll have to come up with GSL-SE (fb) pump, steering gear, and all electrical connections. (the Mazda power steering is an electrically activated unit sensitive to steering force - when you're at speed, power steering is minimal, and when you're trying to parallel park, it kicks in.)
2) I know that some folks have been changing out the Mazda OEM recirculating ball steering system for a rack and pinion system. But I don't know if there's a power version of that available.

Hope this helps.