Killing Dist pickups ?

Another way to check your pick-up is to drag anything with iron in it, across the pole piece, in either direction. Or just wave it(the iron thing) if you can, within the limits of zero to .030inch. This will generate the signal that the amplifier needs, and it will send a spark each time the iron passes over it, assuming the amp is fired up and grounded.
I do this by pulling the amp out of the D, and turning on the key. But you could just pop the reluctor off for access.

You can use the same method to test the amp,using a known good pick-up.(I always carry a spare)

Of course the coil has to be proved separately. I do this by isolating it, jumpering the coil+ to the battery, and dragging a wire from the Coil -, across a grounded file. A stream of sparks should issue from the near-grounded coil wire. Your file is acting like a breaker point-set, and that is all the coil needs.
Once all the components are proved, then you are down to wiring.

If in fact you are "burning out pick-ups", then check your alternator for an A/C output, which should NOT be there. I have no idea how A/C could get into the pick-up, but if it did then I doubt the amp could respond to it. Yet all the components could check out perfect with the engine NOT running.

Tachs have occasionally been known to be troublesome.

Good luck.