Much of this doesn't make sense. The factory intended that the "hub register" fit tight to the wheel, centering the wheel via "hub-centric". Thus, all factory wheels - 13", 14", 15", ralleye, whatever should have the same-size center hole. .
But they don't. The center register is not the same on SBP drum cars and BBP disk cars. Both the 9" and 10" SBP front drums have a hub register of 2.31", the later BBP disk cars have a hub register of 2.80". Even more ironic, the BBP drum cars, like the B/E bodies, use a 2.80" register. So once again, SBP A-body brakes are the odd man out. To make it REALLY strange, the KH SBP disks list a register of 2.9". But that's just the center hole on the rotor, I don't know what the register dimension actually is on the hub for those. If it's larger than 2.3", then that means there are different SBP wheels for front drum and front disk cars. #-o
As far as Wilwood is concerned, they should tell you that you're going to need new wheels if you order a kit for SBP 10" drum spindles and their hubs have a register that's larger than 2.3". With most of factory wheels it's not a problem, since you can't mix and match wheels with different register sizes because they're also different bolt patterns (except maybe the SBP KH disk wheels). But since the Wilwood hubs also offer the 5x4" bolt pattern, you'd think they'd come with a hub register that would fit the existing SBP drum wheels.
Is there enough meat on the spindle to allow you to turn it down for the correct register for the stock wheels? Seems I read somewhere that someone else did that.
It's not the spindle you're turning down, its the outer hub register. On a the later factory rotors, '73+, with the one piece hub/rotors, I would say yes within reason. There's a lot of metal there. People have definitely done that for aftermarket rims.
But with an aluminum Wilwood hub I would be a lot less inclined to turn down the outer dimension of the hub. They're already tapered. And of course Wilwood would walk away from any warranty at that point.
