Kareem was longer and more athletic with more skill. Shaq was super athletic for his size but a young Kareem vs a young Shaq goes to Kareem. Add the skill and it isn't close IMO.
Timmy is the perfect guy for this team and would abuse Durant in the post. Certainly Durant is a better shooter, but he provides little rim protection compared to Tim and overall is not near as good of a defender.
I understand you are trying to go small ball, but honestly your Shaq for Kareem is just wrong. Shaq was not as good as Kareem.