Thanks for the help! Yeah I originally ordered a z22 but was actually a z20, It was listed wrong at the wreckers. So to keep me from sending it back they knocked $100 off. Being a low mileage engine and it being on hand i installed it. Eventually i'll put a fully rebuilt z22 in it now that i have it out of the truck and can take my time building it.
So as far as i can tell with the 8 plug by actually following which plug the rotor fires when, the exhaust side fires after the intake side. So they are not actually firing at the same time.
My dads friend years ago said the exhaust side fires when the exhaust valve is open, as the burnt fuel moves out of the chamber. But it sounds like they changed up the "frankendizzy" a few times in its short production run. Id prefer it if they both fired at the same time tho!
I guess what i had read, but cant remember where is that the vaccuum advance on the 8 plug only advances 6 degrees since it is trying to burn a lean mixture, and the 4 plug vaccuum advances it 12 deg since its burning a mixture with more "fresh" air and fuel.
I guess I'm just trying to figure out the better part to use in the end.
I appreciate the feedback! Must be time for a microbrew and some wrenching!