Good Sweptline site
http://www.sweptline.org/forums/index.phpPower steering is a challenge on these trucks. The factory setup used an assist cylinder with a control valve incorporated into the drag link. Hard to find, prone to leaks and costly and difficult to rebuild.
There used to be a couple of kits that used either a Ford or Toyota 4x4 box but I think they're out of production.
Scarebird has a bracket kit to put discs on the straight axle.
https://scarebird.com/index.php?route=product/product&path=64&product_id=117Some guys swap the cab onto a 73-93 frame which will solve the problem but lots of work.
Another way is to just use the 73-93 front clip.
If I was doing one I would use an 04 and up cop spec Crown Vic clip. This gets you rack and pinion, big brakes and a suspension that is designed for a heavier vehicle that needs to handle well.
Kevin