If the distributor was a tooth off your timing would be way off.

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Official Cookie and Mater Tormentor.

What is the cc of the dish? I am coming up with about 10:1 guessing on the dish. I think you should fillup with at least 93 octane, certainly untill you figure out whats going on. The octane boosters do all most nothing. When you pull those plugs and read them, if there not white, install a colder set, if they are then your lean. Know anyone one that has a wideband O2 sensor and gauge. Maybe a chassie dyno with and O2 meter.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

Run a compression check, what is the "cranking compression" of this engine? (cylinder pressure in psi)
DD

I chased a problem similar on my mothers 47000 mile car that had been sitting around for years. I kept thinking that the timing was too high and I had checked several times and everything was to spec. 0 degrees at 750 rpm. Total advance at 3000 rpm was up close to 40 degrees which I thought was a little high. I read the plugs and they appeared to be too lean with the electrode getting white. To make a long story short, I discovered that the heat riser was stuck in the warm up position or cold position and I figured I needed to take care of this right away. So I removed the exhaust and intake manifolds and did a repair on the heat riser. But I think the thing that fixed the car was the new intake and exhaust gasket. When I got it back together and torqed the manifolds the car was fixed. No spark knock going down the highway!!!! So my recommendation is make sure you don't have an intake leak which would definitely make your mixture lean, and you would not be able to make up for it with timing.
Hope this helps.

Kevin Milton