I hope those are dead hang pullups...And I do mean dead hang. Get an accurate run time. In essence: to run a 285 PFT you need 20 pull-ups, 100 crunches in 2 min. and a run time of 20:30 or better if I am correct. That would be what I would shoot for if I were going to OCS. Your placement in your class has much grander implications in your career than you would think.
From what I know, it doesn't impact your MOS at all. It is to the best of my knowledge that 100% of your placement is earned through TBS. OCS in the larger part has been the gateway to TBS, at least from what I've been informed about. This does not mean you shouldn't strive to work to be the best you can absolutely be however (of course), as the slackers in the platoon get the boot out real quick.
For the most part, the other posters are absolutely correct. You won't be taking any sort of supplements at OCS. I too train for Quantico, but I'd be all for taking recovery supplements, as they have worked wonders for myself. Nothing spectacular, but supplements that will allow you to train harder and more often. I'm big on preparing, and I want to go into OCS the best I can possibly be.
The few things I would recommend would be endurance compounds, which in turn work double to increase your recovery. My favorite supplement is called BodyOctane, made by "MAN". It contains two compounds proven to improve endurance and recovery - Beta-Alanine and Citrulline Malate. I wouldn't recommend much else beside whey protein (sometimes it's hard to eat after a killer run). You won't become dependant on it, but you'll rather reap the benefits and be able to train harder and longer... you'll keep your results too. There is no supplement to make endurance training easier - it's going to be difficult no madder what. A proper diet is basically the only thing that will truely improve your abilities... make sure it's as clean and as beneficial as possible.
Personally, I've been separating my runs and my lifts... I use the Runnersworld.com "Smart Coach" running program (HIGHLY RECOMMEND) and I utilize many Crossfit.com weight lifting workouts. Definitly check those out.
And feel free to PM me with any questions about OCS. I completed PLC Juniors this past summer, and I'm looking forward to getting down there for Seniors this summer. In case you don't know about it - MarineOCS.com is a great site to read through for additional info. The site provided me with invaluable info before my first trip, and I've got so much more to go through before I head out. So much information/great people there... definitly an amazing site.