I just put a CDI switch box on my 78 1400 and it has a super hot spark. Thier tech support walked me through the install. It's purrrin' like a kitten in the driveway and starts at the first bump. I'm ready for sea trials this week.
one more thing... If you goggle the CDI switch box you'll find it for about $200 and new orginal merc is $500 and a new coil that isn't made anymore is an easy $100. It only made sense to me to upgrade with after market that conbines the box with the coil. Has a one year warranty too!