if you did a spindle swap and nothing else (steering box, pitman arm) then there must be a difference in the length of the steering arms on the spindles themselves. it's just a leverage length issue. if you put a shorter pitman on the steering box or the spindles have longer steering arms then yes it would increase your radius. the rack and pinion will always make it a ten point u turner as you cant get as much tie rod movement off an r&p.