Sorry i didnt post on this topic sooner, I decided to index the plugs on my 360 magnum, i bought 20 brand new autolite 3923 plugs and tried every one untill i got one that lined up in between the 10 a clock and 2 o clock position on my engine.
I am not 100 percent sure, but i think it did help smooth out my idle even more and i think it helped with throttle response. Even if you dont feel any gains i think it is still worth it to index plugs because that way you know you are getting the best possible burn within the cylinder... thats just how i look at it. I didnt want to screw around with those washers and i wasnt too concerned about the plug being indexed perfectly... like i said i just made sure they landed in the 10 to 2 o clock position on my heads and called it good.