I put an ad on craigslist for disc brake spindles wanted and had several responses within a few days. I used repro disc brake mounts and dust shields. I used the wilwood calipers but could have used regular calipers.
You could also go with these guys:
http://ecihotrodbrakes.com/early_che...nversions.html
They are not cheap (575 for the kit), but use aluminum hubs with the early or late bolt pattern. ECI has a good reputation in the street rod industry, well built stuff that works.
I was told that the only difference between the drum brake spindle and the disc brake spindle is the upper bracket mount. In the past I had seen companies that sell disc brake kits that would modify your spindles, but I can't remember the company.
The disc brake spindle is machined about 1/4" deeper to accomodate the thickness of the bracket. Marc at SC&C told me that 'you could use a grinder to modify the spindles if you measure carefully'. I got factory ones instead of modifying mine.
Good luck,
Mike