Thanks now I see what you have.
1--Do NOT check spark initially at the plug wires. Check rather at the coil tower directly and use a grounded probe like a clip lead and screwdriver.
2--You say you have now temporarily eliminated the 6A. So looking at the distributor sheet, you have
http://www.msdperformance.com/WorkArea/DownloadAsset.aspx?id=15032386333
orange from dist. to coil neg
red from dist to coil pos
black from dist to ground
You should be able to jumper a clip lead directly from a battery source (starter relay, etc) to the coil POS, crank the engine and get sparks at the coil
3--If so, THEN move to a plug tower. Pull a plug wire at the coil, and hold your grounded probe there at the dist. tower. Make sure you rotate the engine far enough, IE the dist, only comes around every 2 engine rotations. The advice above about a punched rotor was good, but you should already have spark at the coil, so now if you do have spark at a plug tower at the cap, you know the rotor is OK.
If you get spark that far, then go back and confirm, you SHOULD have battery power to coil + (this is still without the MSD) with the key in the run position.
4--If not, your possibilities are bad connection in the bulkhead connector, bad connection at the ignition switch connector, or bad switch
5--THIS POSSIBILITY does not explain why it would not "start and die."
The "run" voltage and the "start" ignition power comes off TWO separate ignition switch contacts, the old "blue" (run) and the old "brown" (resistor bypass circuit).
Normally if there is problems in the "run" circuit the engine will fire during start, and die in run
Normally if there is problems in the "bypass" circuit the engine will not fire in "start" but will start with the key in "run" and then jumpering the start relay.
Where and how did you connect these to the "new" feed to the MSD "small red" these wires originally went to the original ballast resistor which should now be bypassed
