Help with MSD ignition system diagnosis

I have a 340 with an MSD ignition system - Probillet distributor and an old school 6AL box (NOT DIGITAL!). I've used this on my Dart for 15 years or so and it has operated flawlessly. The engine now cranks, but no fire. Before I send off the Box and dizzy to MSD for diagnosis and repairs, I want to make sure that the problem is not in the wiring to the components first. Can someone suggest a set of tests that should be made to do that? (e.g.: test for 12v at the following locations with the key on or off, etc.). About a year ago I replaced all the under dash wiring including the ignition switch and I want to make sure that system isn't the source of the problem rather than the MSD components.

Thanks for any help...