I did think about checking for arcing, iirc I ran it in the garage with the lights off.
I know for sure I pulled all the plug wires and looked for burns or cracks.
The wires are fairly new, but the best part is they have porcelain boots, very pleased with the quality.
I have lightly filed the areas where the rockers came in contact with the retainers, bolted them on, rotated the engine manually, and checked for clearance.
I had to take the assembly off 5 times to clear the #3 intake.
The goal is to run it once more, verify the ticking is gone, quickly check other items if needed, shut it down, degrease it, and invest in some adjustable rockers.
I actually found a thread on here from March, exact same heads, engine, issue, wear marks on the rockers, everything.
https://www.forbbodiesonly.com/moparforum/threads/stumped-with-a-383.169719/#post-911309471
Although the conclusion was different in that thread, the issue seems pretty obvious to me now.
Where the pushrod meets the rocker, some rockers have a circle wear pattern just outside the oil hole, some have a full wear pattern from the oil hole to the center, like the pushrod is drilling a hole thru the rocker.
The rockers that are contacting the retainers are the ones with the full wear pattern.
This is essentially drilling thru the rocker, lowering it on the pushrod, which makes it contact the retainer.
My understanding is eventually the pushrods will punch thru the rockers.
Honestly I don't recall how everything was upgraded on the build except the rockers. Although the stock ones lasted 8 years, it wasn't a good choice, but I didn't know any better.
Now I'm trying to learn myself on adjustable rockers so I can decide on what to get, install, measure for pushrods, and get back on the road.
Maybe the Mancini ones, however at this point I don't know what 1.5 vs 1.6 means or why my stock rockers are offset and theirs are not, but I'll figure it out.
https://www.manciniracing.com/b16alrowibih.html
The alternative is the 'matching' non-adjustable roller rockers.