[Jack21]

You really don't want to put a Pep Boys rebuilt distributor on your roller cam motor. That's if you could get Pep Boys to sell you one in the first place. You first have to tell them what car it's for, then they try to look it up in their computer, and you get nowhere. But assuming you could get a Pep Boys distributor, it would run poorly for a short while (wrong advance curve and vacuum unit), and then not at all (wrong distributor gear).

Go with the MSD billet. If you can get MSD to install a steel gear on it for you, do so. If not, get a Motorsport steel gear for roller cam and install it. Get a spare, as you'll likely be changing it after 5000 or so miles. The second one should go a few years. Next, even MSD won't sell you an adjustable vacuum unit for this dist because they don't make them. You need a Crane or Accel adjustable vacuum advance for a '57-'73 GM distributor. Set the centrifugal up for 20 deg @ 2500 RPM, and your vacuum for 12 deg.

The MSD 6A or AL is fine out of the box. The Blaster II coil is probably OK. Crane PS91 will work too.