Brakes are too important to do a poorly conceived conversion.
I would listen to the guys at the machine shop, you don't want things to fall apart.
About the spindles from a Kodiak / TopKick they are much larger. I used the whole front axle from a TopKick on another truck (61 F350). I did not think any part of it would be suitable for an AD bigbolt, and for sure not the whole thing.
The best option I have found for disc brakes on an AD bigbolt is the P30 or 3500HD axle swap.
John and I are working on a pretty good tech tip covering these upgrades / swaps. I expect it will be done very soon.
Grigg
