Looks like you're getting ready for a recon indoc or something similar, Jack. It also looks like you're getting some good advice here, especially from Dave. I wish I had these resources when I was going through.
When I did them (did both div and force) there was a ton of ruck running in addition to the PFT, O course and swimming stuff. That was way back in '99, so looks like it's different now. For what it's worth, while I wish I had been as strong as you back then, I don't think I would have focused on that as much in my prep (especially if I was already at that level). My prep included a sh!t ton of ruck running and swimming (twice a week in full cammies, pretty much every day otherwise), with some weighted pull ups and presses to maintain upper body strength.
I am 6'0" and hovered around 200lbs my entire career. I always had my situps and pullups, but the run was always my biggest struggle. I ran an 18:07 during the indoc and always struggled to break that 18:00 mark. Seems like you're in a similar position and would want to focus on running and swimming. I was a very strong swimmer and still found that portion to be fairly difficult (Dave's comment on technique is dead on). Side note: I recall a bunch of guys getting really fatigued while treading water because they would fight the sharks. Let them take you down and have their way with you and you will save a ton of energy. I'm sure people have told you that, though.
Not sure how helpful this is, but hopefully helps your thought process. Wish I could be in your position.