These trucks have limitations with steering geometry. To go beyond takes fabrication - or a different steering design. I think with a bit of lateral thinking a rack and pinion will work. It will obviously need a uni joint yoke to connect from the steering column shaft to the rack but it will kill all the steering slop and solve a bunch of geometry issues. I have thought about the problem with retrofitting power steering as well and going for electric/hydraulic will avoid a belt driven pump. I'm not a fan of column actuated power assist. Seen what happens when they malfunction and it's not even remotely a good idea...