drop spindles and disk thickness..?

[Possmguts]

When looking at drop spindles for the 67 I see a lot of them requiring converting to 71-72 disc brakes or equivalent... I have disks that are 1.5" thick already... what is the 71-72 thickness? I see them for 1.25" and know those wont work for what I already have, but they never say how thick the 71-72 is...