I want to do the same swap and I already own the same parts.
I have a plastic model just in front of me and I think itīs 10 mm from the spindle to the Corvette bracket.
But I will use the disc spindles (and hubs) and here is the lower bracket bolt closer to the disc. So I will use another bolt for the upper thread with a spacer to match the same level.
I have to do some milling at the outer diameter of the hub, because the disc doesnīt hit the surface from the hub.
But it should work. I already installed the plastic model to check all necessary clearences.
Sorry, I donīt know the drum brake setup exactly.
69`Camaro, 92`LT 1 / 4L60