1968 C10 Fleet side long bed rear axle to bed measurement

[Jbrem010]

Hey all, the previous owner heated the rear springs on my 1968 C10 and I've added 20" wheels, low sidewall tires and want to lower the rear of the truck. Since nothing is stock, what was original rear axle to bed dimension? This should allow me to determine which drop spring I should go with. I recently installed a 2.5" drop spindle with 2" drop springs on the front and I cut a ring off to drop it another inch (see attached). Thanking you all in advance.