Ignition:My accel powered HEI was damaged at some point, unrepairable too so since I had the HPefi system in running fuel only, it wasn't a hard decision to upgrade. I decided to go with a GM computer controlled HEI. The local shop had everything I needed to connect to the holley harness. There is a plug in harness to connect but I didn't want to wait for it, so I bought the HEI connectors and a 4 pin metripac. The GM HEI only connects to 4 wires in the holley harness so I just cut them by their connector and wired in the metripac. Providing spark is an MSD blaster 2 coil. The ECU fully controls fuel and spark. Ignition timing is now: Crankshaft to timing gears, 4 deg. adv. to camshaft, camshaft to computer controlled HEI dist. This setup is controlling ignition timing accurate to /- 1 degree.Also installed is a set of Billet Specialties cast alum. valve covers.