Drop pitman arms are shorter, between the sector shaft and the drag ling ball joint centers, than standard. All the are is a regular pitman arm with a S bend. You are probably hitting the stops inside the steering box, which isn't good.
Lengthen the drag link a little and see if that helps. Yes, you will have to remove the steering wheel and re-clock it to get it centered again.
If at first you don't succeed, use a bigger hammer.