Is This an Indicator of Detonation?

I see Oil burning on piston tops.

Check the spring installed height and psi on a butterfly pattern vs the 2 that are different or stable and center. You might find you are light on pressure, seat pressure. The numbers shouldn't vary from one another more than 8psi. You can have them close to insufficient already and then let a few slide 5 psi lighter and bam...you have issues.
In performance land...we want the valve tip pattern to be a horizontal line, as in ..no valve spin. Spinning ain't winning 'in more ways than one'. Spin is for stock 85psi seat & 200 open psi crap that lifts .390-.410...
The hone job may be too rough for the rings...hence taking "long time" *add in asian voice* and oil on piston tops.

Disclaimer
Never forget ...we love seeing pics of teardowns and will gladly have you ripping back to square one, so dig carefully and have plenty of money. Lol