GM HEI mopar dizzy hybrid

I've always run the D.U.I. (Davis Unified Ignition) HEI's in my dirt cars. Had it on my engine builders distributor dyno and it never missed a beat up to 8k RPM. I've turned it to 8,300 one night in the dirt car and it never skipped a lick. I kept the distributor and LIVE Wires when I sold the car and will be taking the guts out of it and putting it in the Mopar/HEI housing soon as I get a chance. I dunno what they do to their stuff... but I've never had an HEI work well at all above about 5,500 without starting to fall off.