Second, If we are going to grab some random advanced metric to boost a players credentials I will go with PER, WS and VORP. Kobe 22.9 PER 172.2 WS and 80.1 VORP 80.1, Duncan 24.2 206.4 and 91.1. TS% favors Kobe because of 3P% and FT% not because he wasn't a chucker or didn't maximized his teams offense.
Third, If you discount players landing into the 'perfect situation' and winning championships why bring them up? Kobe played with Shaq. Shaq was the best player on those three championship teams should we not discount those? I think the measure should be best player on championship team. Duncan would certainly be that at least 3 of 5, I would say 4 of 5; Kobe, 2 of 5.
Fourth, you can't really grade adapting for today or adapting for if they played in the past so lets just stick to what actually happened. Fun to think about but really subjective.
Finally, Kobe is always overrated in these conversations for whatever reason. I think narrative and game style play an outsized role for many players like Kobe. I think MJ is the GOAT but he also gets a bump here which really isn't earned and Lebron gets discounted.