western chassis rear axle flip question on centering

hey fellas I am doing an axle flip on my 84 c30 I am not using this kit, I just bought the u bolts and spring perches from a local offroad shop. my question is, after looking at these photos from wester I noticed that the saddle that they use to sit on the springs, over the centering pin has the centering pin hole offset either forward or rearward. obviously I know because I am lowing it the springs will be further up which will move my centering pin farther rearward. does anyone know how much?? my perches have 3 centering holes to slide ale forward or back but I am making my own u-bolt plates and I am drilling my own holes so I need to know where to drill the upper hole for the nut side of the centering pin

i just measured mine it's 1 inch back center to center of the hole

thank you

No problem it's late but I hope it helped