HEI in Mopar
A factory HEI module has less rpm capability than a stock mopar ecu when used with non HEI coil. You need to buy a perfromance module to get any advantage over a stock mopar ecu.
Unless you get a coil that is specifically designed to run without a ballast using the HEI module does not elminate the need for the ballast. You have to rememeber that GM designed a system which was comprised of a coil and module, unless you use the GM coil or an aftermarket coil that is designed to operate without a ballast you still need it.
Get the same coil and you can elminate the ballast with the mopar ecu too. Also, the vast majority of canister type coils need the ballast.