Rookie, yes only a 4/7 swap , Pretty sure that all 8 cyls. will be used

Ok, my 558-307 harness arrived. Problem... I don't have a J1B connector plug in my main harness or the terminated wires? Am I missing something? Do I need to buy another harness or something? Does this run through the I/O bare leads? I have harnesses 558-504, 558-307 do I need to wire in a 558-400 somewhere?
https://documents.holley.com/199r10837.pdf
https://www.holley.com/products/igni.../parts/558-307
https://www.holley.com/products/fuel.../parts/558-400

Got it. P1B has empty pins in the connector that plugs into the ECU. That needs to be pinned to the 558-307 harness. J1B is also P1B

I suggest buying a good metripack ratcheting tool. It will save you lots of frustrations.
Also not sure if you knew but to pin those connecrots you need to push in the white slit on the ECU connector otherwise you`ll spend 30 minutes trying to push it in without success and almost throwing the ECU across the room and going back to carbs
Ask me how I know

I'm borrowing the tool from work. Hmmm would have been caught about that white tab. Thanks

Ok, how/where did you mount the coils? I see on the underside of the engine. Did you use the exhaust bolts?

Looks like the bracket is attached to the exhaust manifold bolts.

Jason, My son found a oem app for regular bbc valve covers with coil mounts, Ive used stock cast aluminum factory valve covers with drippers ground out, stop tabs ground off around perimeter with extra thick rubber/steel bonded gaskets on them, they clear all manifolds and every kind of rocker arm, shaft rocker etc except stud girdles. I bought a set of used 496 valve covers with coils mounted on them, extremely shallow, wouldn't clear anything in a million years BUT as long as these other ones clear manifolds/headers with coils on them , they may be a nice option for you. Ill post a pic when I get time, smitty

496 valve covers will work if you get the spacers and 2 gaskets.they clear after market rocker arms.spacers were pricey though.

This thread went down a deeper rabbit hole than I expected. Nice work!