Six weeks is maybe a bit long for an SST focus. You should change up your threshold workouts. SST is awesome, and I've gained a lot from it, but you'll stagnate. Maybe 3 weeks of SST followed by 3 weeks of supra-FTP workouts (like ZCI™s). You want to change it up between pushing FTP up from below and pulling it up from above. Once you start getting comfortable with a workout, I find I'm close to a plateau and need to change.

No way to speculate on possible gains. Too many variables, but you can get stronger.