reluctor- pickup gap?

How about this one. I bought an FBO ignition package (dist/box,ballast/cap/rotr) and had it custom curved for my 408. When I received it hte first time (!), the engine would not start. After 4 run down batteries, I determined that the reluctor was installed using the wrong slot on the reluctor (it had 3!) I rotated to the correct one, and the engine fired right up. After about 800 mils, the reluctor got into the magnetic pickeup, and destroyed both. I sent it back, and they fixed it fro free. When I got it back last week, it came with a 0.090 gap!!! (not 0.009, mind you). I called Don at FBO, and he said it would work fine, don't adjust it. Well, it did fire up, but it missed and backfired occasionally. So I readjusted the gap to about 0.020, and it got a lot better, but still backfires occasionally. I need to set it to 0.008 I know, but am afraid it will hit the magnetic pickup again. Ever had this problem?