At 6 INT, you’d have a decent chance in a toe-to-toe Theurgic duel against 3 out of 4 of the ones I have in mind. (The last one would require, let’s say, a 9 INT or special circumstances.)
In terms of dominating the post-Hegemonic order through Theurgy, the number of other Theurges you can train/attract to your faction is more important than your personal ability to win an Avada-Kedavra-off. A 6 INT MC could do very well there. So of course could a charismatic MC. But only an INT MC could train your own, as opposed to having to cut a deal with the primary perpetrators of the existing blood harvesting system.
You will definitely have the opportunity to loot the Lykeion in Game 4. And the stat bumps will come early in each game.
I’ll refrain from comment until you’ve spoken with Cerlota. 