new ballast resistor died in 10 minutes

Use a voltmeter to check the battery voltage at fast idle and warmed up. It should read in the 13.7-14.2 voltt range. If it is a lot higher, then that would stress the ballast (and everything else). Any such overvoltage condition needs to corrected ASAP. I bring this up as you replaced thr VR for some reason and you could have charging system issues that remain unresolved. Unless you measure the charging battery voltage while running at fast idle, or kinow how to observe the ammeter and work from that, then you don't know if the charging circuit is right.

Also, be aware that the stock ballast resistors cam in 2 different resistances. So you might have the wrong NOS one.

Was this a /6 or V8 or what? And is this the stock coil? Year and model car?