You are exactly right I have heated and bent lots of suspension and steering components when building street rods and it doesn't faze me/us in the least, but you need to let them cool naturally, quencing them will crystalize the metal. Also spreading the heat out is better than just concentrating in one area. I don't think you can heat an a-body pitman arm & idler arm without the heat ruining the ball joint in it.
DRoCk, like C130 Chief says the Mopar Chassis manual mentions using shims one way or the other to move the steering box to gain clearance for the pitman arm. For moving the idler arm the same amount it shows in the same manual slotting one hole of the idler arm bracket so it can be moved.