1. Call Jeff Jordan at RPM Proformance and get some of his heims, they are kevlar inserts instead of nylon or neoprene.
2. Get a longer kingpin bolt and tighten the nut til there is no slop, but still allowing the steering to turn freely; then run another nut up on the kingpin bolt and double-nut, or jam, the first nut so it doesn't work loose. This has always solved the problem of spindle slop for me.
Mike Hudson