No need to work with suggestions, and it will be misleading if you just check for voltage being at each end of the ballast with the ignition switch in the ON position.
Put the meter in resistance mode, at the lowest scale, then cross the wires and take resistance readings a few times and note the average; this is the resistance of the leads alone. Then disconnect the wires from the ballast and check the resistance through the ballast. Subtract the lead resistance and you will have your ballast resistance. Cold, a stock Mopar ballast will be in the 0.5 to 0.7 ohm range. (VERY low, which is why you need to subtract the lead resistance to get an accurate number.)
If the ballast is good, you can then test for a good coil and wiring without the ECM and distributor. Disconnect the ECM, set up a wire jumper so one end is grounded and can reach the coil - terminal, and disconnect the distributor end of the spark wire from the coil and set it 1/4" from ground. Turn the key to ON, and then momentarily ground the coil - for a fraction of a second with the wire jumper and then unground it. Each time you unground it, you will get a spark. (Be careful.... if you are touching the end of the wire when you unground it from the coil, YOU may get a nice little shock!) The sparks you get should be good hot, blue sparks.
Then use your multimeter in resistance mode to measure the reluctor resistance through the 2 prong connector going into the distributor; do this while this distributor is disconnected. If it is good it will read a few hundred ohms. This is not a guaranteed test but is usually a good indication of health of the reluctor. Then set the gap from the reluctor to the rotor teeth to around .008" with a non-steel feeler gauge. Brass will do, or 3 thicknesses of standard lightweight printer/copy paper can be used in a pinch to get close to .008".
If all the above are good, then replace the ECM. A NOS OEM is best; the new ones made overseas have earned a poor reputation for reliability. If the ballast is bad, then find one that is RIGHT (not just any ballast), or ignition performance WILL suffer; the Mopar ballast resistance is unusually low. The MSD 0.8 ohm ballast is the closest I have found to the stock 0.6 ohm (cold) Mopar ballast resistance. A BWD RU19 is the best 'box parts store' type and is so-so for spark performance. (I usually go on eBay and find a NOS Mopar ballast.)