Correct me if I'm wrong, but I seem to recall that the Gopher Coaches actually prefer D-linemen who are a little lighter and more mobile. If you want size, you can probably go out and find some 330lb type to clog up the middle, but it's a trade-off between size and quickness/lateral movement.
I did think that Stelter showed some promise when he was forced to play inside vs. Iowa. He's listed at 277 on the roster - I wonder how much more weight he could put on? By the way, on the roster, the biggest D-Line men are Richardson at 291, Scott Ekpe at 290 and Shoobie at 290.