Problems with 360 LA distributor

Im having problems getting a consistent 8 thou gap with my 360 LA distributor. I've tried a new pickup and reluctor but the base plate is not very secure and the gap keep changing to the point where it's either touching the reluctor or too large and no spark. Seems there is a little shaft wobble that is not helping. So any tips on improving the existing mopar dizzy or suggestions on fitting a replacement appreciated.

I've seen this one for sale locally, but not sure if it will fit the it has a purple ID tag number 375521, mine has a green tag 360xxx

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