What you will need is a standard A-2 or a rifle that looks like what is being issued. I believe the flat tops are now allowed do to the use of the A4's in Iraq.
The price you are looking at might buy a used AR type service rifle. If I were to buy a new service rifle, I would look at the RRA match rifle. The asking price is well over your price range but I understand shooters are very happy with them right out of the box. I would shop around with different dealers as the price will vary. You should be able to find someone who would sell a NM RRA for a little more than you are planning.
The reason for needing a special rifle over a regular A2 type is the twist rate of the barrel. If you get much slower than a 1-8 twist, the heavy bullets needed to compete with the 308 168 SMK's won't stablize. I would suggest a 1-7 twist. These will shoot the 77 and 80 SMK's without question. The 77's and 80 SMK's seem to be the most commonly used for a full across the course match which runs out to 600 yards. Another reason for the need of a NM rifle is you will have a better sight system. It's pretty hard to shoot well with battle sights, front post too wide and rear app too big.
Another thought to see if you would like High Power, and I know I sure do,
is maybe get a CMP M-1 and shoot a John C. Garand match. Same game, closer ranges and everyone is one the same playing field.
Go to a match. Every High Power shooter I know is more than willing to help a guy out. There might even be someone there that will loan you a rifle until you decide what to do. You do have to be careful though, the bug might bite you.
