power steering bump steer

[gab50]

I have just got back on the road after a power steering install on my 50 1\2 ton which used the steering box from a late 70's pickup and the steering arm and drag link from CPP. First impression is it steers good on smooth road with hands off no wander. It has a little bump steer on bumps. I think this is due to a bunch of things, some being the setup has a very short drag link, presently has very little caster ( 1 degree ) and wide tires on the front (265 ). I have a 4" dropped axle from Sids enroute so will not address caster until that install but plan on 6 degree caster shim at that time as truck should sit with a 1.5 degree nose down rake so the effective should be 4.5 degrees of caster and front tires will be reduced to 205's or 215's as turning will be a problem with fender contact after lowering. At this time the drag link is parallel and will be after the axle install. Anyone else with this setup have any opinions or things you have done to make it better.