Will the /6 ECU work with a V8?

The ECU between a \6 and v8 are the same whether it is 5-pin or 4-pin is based on the year of manufacture. The early electronic ignitions used the 5-pin ECU and a 4-pin ballast resistor. Later systems did away with the 5th wire and reverted back to a 2-pin ballast resistor.

A 4-pin ECU is a drop into a 5-pin wired system and requires no changes and most aftermarket ecus are 4-pin. If the ECU is a 5-pin then it needs the extra wire and 4-pin ballast resistor.

The output of all inductive ignition systems drops off as rpms rise. If the system is designed to to provide adequate output at high rpms to much current flows at low rpms and the coil will over heat and fail. If it is designed to work at low rpms you may not have enough output to fire the plugs at high rpms. Mopar got around this dilemma by using a ballast resistor. The ballast resistor changes it's resistance with temperature so at low rpms it heats up and reduces the current to the coil preventing it from over heating. At high rpms it cools off and allows more current to the coil for a higher output. Modern electronics can vary the dwell with rpm and do not require a ballast.

A Blaster II coil requires a ballast resistor, you should use the one MSD recomends to get maximum out put.