No! Do not switch to a 6v coil!
First of all, the type of coil and how its hooked up shouldn't have anything to do with whether or not the car cranks.
Secondly, 12v coils can be of two varieties, internally ballasted or externally ballasted. Stock mopar coils have an external ballast resistor, (that 4 pin resistor), so the voltage is stepped down, usually to around 8 or 9 volts, before it gets to the coil. This is
NOT the same as a 6v coil!!! Coils can also have an internal ballast, so you can hook 12v directly to them. The coil still only uses 8-9 volts, but you don't have to look at an external ballast on your firewall because the ballast is inside the coil.
Now, if you have an internal ballast coil, and hook an external ballast to it, you won't see much voltage in your ignition system since you'll be stepping the voltage down
twice. Check to make sure your MSD blaster 2 is an external ballast type coil. If it's not, you'll need to find a 12v source for it instead of running it off of the 4 pin ballast resistor.
Now, even if you did manage to hook an external ballast to an internally ballasted coil, I'd think the car would still
run. It would definitely still crank! So, the other thing to look for would be an owner installed kill switch, or the remnants of one. It's not unheard of to put a kill switch into the coil power source, or into the distributor power. If someone did that, its possible that with that wire hooked up is grounding out your ignition system. It might be through a switch, or, the switch may have been removed at some point and you'll have to chase down what's left of the kill switch wiring. Check to make sure that the coil power source runs back directly to the ballast, and the distributor power (off the coil) goes directly from the coil to the distributor. If they split or take any detours, you may have your problem.
Other than that, if unhooking your distributor is the only way to get the car to crank, I'd have to say your distributor must be drawing a whole
ton of amps.
