Wheel offset help****

[Dentguy]

So I ordered last week and billet specialties Bonneville G wheels and they called back yesterday to say with my measurements that they recommend a 6.25 backspacing. I said they were nuts.
Truck is a 67 with stock disc brake conversion off of I think a 71. Lowered with ece spindles and Hotchkis springs. Top of tires are flush with wheel well. No tuck. My current wheels are 20x8.5 with a 4.75 backspacing and a 0 offset.

I have never seen any trucks offset differ from 4.50-5.50 on almost all of them. I got frustrated and said to build them at 4.75 like my current Ridler wheel. Tires are 255/40. But I'm nervous as sh#t I'm going to have 2 front wheels worth $2000 that are going to be mounted on my wall.



Any help is greatly appreciated. I'm losing a little sleep. And I've measured it multiple times. Mounting area to inside of outer fender is 5". Mounting area to inner fender is 14".
Thanks again.
Doug