Check out www.davessmallbodyheis.com

I had a "normal" HEI in my '67, but I know it was contacting the firewall under full throttle, and that was screwing my timing up, and wearing out the distributor. Installing one of Dave's conversions has been some of the best-spent money for my car.

Dave's conversions are MUCH more reliable than either Unilite or Pertronix, and are designed to operate at full voltage (like an HEI should).

I'm using the version that triggers an MSD box, but I've installed the version that uses GM HEI modules on several cars for others, and they work great as well.