When people from here see me (6 ft 2" 230-270 lbs) first thing they say is
" you take horrible pictures dude your wayy more impressive in person"
im not one to brag but if u calll me out im gunna be honest
those lifts 5 - 10 years and 150 lbs ago were done and i wasn't the strongest of my crew by far!
You've got a decent upper body and good upper arms, but I have problem believing your claim of a 600 lb squat even at 300 lb bodyweight - your leg development doesn't offer any proof by way of thickness or density or anything. Of course, it could be that you've got really shitty leg genetics coupled by the fact that you're tall.
You should do free weight barbell Squats and front squats every week, around 10 sets with your max weight and you should do triple drops - do a weight with which you'll reach failure around 8 reps, drop the weight and go to failure for 12 on the next one and drop the weight further and do another 12 - 15 reps. Take 6 - 8 minutes off between sets, give it 3 months and see what happens.