Coil Voltage issues?
This is the destructions
http://www.msdperformance.com/WorkArea/DownloadAsset.aspx?id=15032386286
These work similar to Mopar points / electronic, that is you send power to coil + and the distributor electronic module triggers the coil NEG
Your voltage to the coil pos. seems about right. Do you have the ballast resistor bypassed? You tried checking spark right out of the coil tower?
Try running a clip lead (alligator clip) from coil + to the starter relay "big stud" which is battery.
Make sure the black is grounded to block, and I would try unhooking the tach if it's there now
I don't know a thing about the guts of these. Check inside for obvious problems, IE rust and other trash, rubbing of the pickup coil / trigger wheel, looseness, etc.