Is anyone using this setup? I have a stock HEI and want to install one of my old tachs in my car, specifically the 1971 Dixco Don Garlits signature tach that I've had for probably 20 years. It doesn't use a transmitter box, just a basic hookup. Can I use it with the HEI or do I need some sort of adaptor? MSD offers a tach adaptor (#8920) but all they say it you can use an old tach with an MSD box but doesn't specifically address the HEI. Thanks.