Shims for Rear Hub to Axle Flange

[MotoPsyche@aol.com]

I'm reinstalling my axle/hub assemblies into the differential. Because I've 
painted both sides of the brake backplate with POR-15, I'm guessing the shim 
pack between the backplate the axle flange is no longer correct.

What's the procedure to determine the correct shim pack thickness, and what's 
the right measurement spec? I've not been able to locate this information in 
either the factory shop manual or my Haynes book.

TIA,

Bill Stagg
1960 TR3A