I'm dealing with a similar problem on a BB F@#d, I have been chasing wiring gremlins in an original harness. The MSD A6 ignition is a proven product and is tried and true as long as it's wired correctly. In your case it just take time to source the issue. In my case I'm paying for the sins of everyone who has ever touched the wiring.

~ Craig
1958 Viking 4400
"The Book of Thor"
Read the story in the DITY
1960 Chevrolet C10
"A Family Heirloom"
Follow the story in the DITY Gallery
'59 Apache 31, 327 V8 (0.030 over), Muncie M20 4 Speed, GM 10 Bolt Rear... long term project (30 years and counting)

If you don't like driving yourTruck, you won't drive yourTruck..| Living life in the SLOW lane