I have dealt with a broken ground wire in the past... "Been There, Done That".
What I am curious about is, what is the effect of these alterations?
1. Stiffer spring = advance comes in more slowly (seems obvious). No idea where you would get a replacement spring.
2. The limiter — not sure what this is, or how you would adjust it
3. The washers — more washers = what? Advance comes in faster, or slower? My impression was that this was the only user adjustment.