Re: Match question
There is a guy that I bump into from time to time around here in WA that shoots a Rem 700 SPS w/ a 1-12" tw... I think he found some 64gr Bergers that were the heaviest bullets he could spin in that barrel. I'm not sure how much realistic benefit they have over a 50-55gr running as fast as you can push it, but the moral of the story is you may be able to squeeze a little more out of what you have.
Strategy for staying in the 10-ring... aim for the 9-ring. Actually, I'm not really joking here - trying to stay in the 10-ring under anything less than optimal weather conditions (and your first time out, and somewhat under-gunned) is going to be more of an exercise in frustration than anything else. By all means get out there and shoot, and see what you can do with that gun/load, but maintain some realistic expectations.
I don't know what the local wind patterns are, so I'll just say this: keep an eye on the wind flags if there are any. It might take a string (or two), and you may have to fudge and ask someone (not during your strings) what flags are best to watch, but watch for pickups, letoffs & switches. Those are the things that are going to launch you out into the 8-ring and beyond.