no spark

I just  completed a complete engine rebuild on a 1967 comet capri.  I did some modifications, .030 bore, crank ground, rebuilt heads, 4 barrel intake, headers, and an MDS coil.  When I first turned the engine over for the first time I had lots of spark.  The timming was out 180 so I disconectes the coil wires, and  pulled the distributor to corrected it.  When I turned the engine over there was no spark.  Since then I have replaced the coil with a stock coil, points and condenser.  Still no spark.  I tested my ignition wire, it is at 12 volts on the positive side of the coil.  I also have 12 volts at the negative post of the coil.  There is also 12 volts at the wire that connects to the points. I have checked the grounds to the block and firewall, they are fine.  Now I seem to have a very weak spark sometimes and no spark other times.  I have started to pull what little hair I have left so any help would be greatly appreciated.  One other thing I'm worried about is I've turned the engine over for a total of about 4 or 5 minutes trying to fix this problem, my concern is my cam and lifter break in, am I still ok?  HELP!!!  

tyr to pull the ford distributor cap, you might need to replace the pick up coil under it.