I would start Evan Mobley at PF and bring Kidd off the bench.
I loved your big backcourt of SGA & Klay. Durant at SF. Mobley and Gobert as big men. That is a super-tall lineup. Lots of length. Good quickness. Good activity defensively.
I think I agree. I couldn't decide whether an off-ball guard or a 2-way spacing big was the best option for this lineup. I think I agree it's Mobley because he does everything well at 22% usage. Elite defense, very good rebounding and passing, elite efficiency, 36.6% on 3's for a quarter of his shots.
PG: SGA (24-25, MVP) / Jason Kidd (09-10)
SG: Klay Thompson (14-15)
SF: Kevin Durant (13-14, MVP)
PF: Evan Mobley (24-25, DPOY)
C: Rudy Gobert (18-19, DPOY)
That's one of the best defensive starting lineups IMO, and with SGA on ball, KD as the #2 who can play off ball and Klay who is the best off ball 3-D player in the pool, I think this team is a contender.
2 DPOY, 2 MVP scoring champs who won FMVP, one that year and one twice later, and Klay. Solid.
However, many teams also got better (Jvalin), Roy is rounding his roster out. Things have changed from Commish Buddy power rankings that were current and still relevant just a few hours ago.