Smartest Way to Progress on Squat

Hey CT,

I just went through 1st face recovery and 6 weeks off training due to ac joint reconstruction surgery and sprained ankle.

The only exercise I can do is Safety Bar Squats. My goal is to hit 3 plates in 9 weeks along with shoulder rehab before returning back to sport. I tested it today and I could do 155 for 5 but it was really hard.

What do you think is the best way to structure training around only this one lift and what progression model I should use to achieve my goal?
I would be really grateful if you could help me.