65lbs is a lot, but not for back squat.
Best way is to squat 2x/wk doing heavy singles at 93-95% of 1 rep max.
Program would be simple and look like this
Week 1 lift 1 (I assume 315 1 rep max)
Warmup 50, 60 75 and 85%
Reps 4 singles at 93-95%
Week 1 lift 2
Same warmup
Reps 5 singles at same weight as last session
Con't this till u hit 10 singles, then up weight by 5 to 10lbs and drop back to 4 singles and work back up to 10 singles....rinse and repeat.
Limit any extra leg work...do at most 1 pump set at end of session.