True, it isn't just about size. Lyle Sendlein from Texas, who is right 'round 300lbs, is a guy who is a very good pass blocker (impressed many @ the combine) who isn't nearly as weak in run blocking as Datish. Another guy who isn't really huge is Dan Mozes of West Virginia, who is an extremely good run blocker, but will probably fall to the later rounds due to some poor performances in Mobile and Indy. I think the kid can be a really good center in the pros, a backup for sure if not an eventual starter.
In terms of size, there's Fresno State's Kyle Young, who is 6-5 and 'bout 335. He's a guy who has played some tackle and guard before also. If he's available in the 4th (maybe) or 5th (not so sure) round, he'd be a decent player to pick up.