Don’t understand how pitman and idler arm work at spec torque settings?

LovetheA's said
So I removed the idler arm and looked at the hole where it bolts to the k frame. The hole looks pristine and perfectly round. I’m thinking that with the 67 k frame maybe the idler arm should be a little tighter than on the 68 and up k frame. I also held onto my old idler arm and compared it to the new one from PST. Actually the bolt through swivel point on the new older arm to the left in photo is smaller by .030 thousands as compared to the older idler arm to the right. Therefore I can’t see it not working just as well as the older one? I guess I can put in the new one tighten until I think it is 40 ft lbs hook up steering and see with my 16:1 manual box if I can turn the wheels. Car is up on jack stands. Live and learn!
Carl

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couple of things I noticed: maybe it's just the perspective of the photo, but the idler on the right appears way more stout than the new one on the left.
why did you have to dent the headers so much? It may be a little late in the game, but maybe you could have shimmed the motor mount biscuits to reduce interference with the tubes.
if the male taper is too small for the female taper, when you tighten the stud nut, you could be pulling the taper thru the hole so far that it is binding the ball socket shoulder against the x-member bracket.