He probably has a better chance as an OT.
im not saying he wont be an OT in the pros. What I am saying is with his size, if he has any athleticism whatsoever, he could be used for special situations, such as FG blocking and goal line TE.
I don't think he can be an overly effective OL, unless he is a Shaq-like athlete. He will probably deal with knee issues all the time. He will most likely be lumbering. Now, if he can drop 40-60 lbs over the span of 2 years, while maintaining and building his muscle mass, especially his legs and core, then I feel he can be athletic and strong enough to deal with not only the big bullish DEs and DTs, but also the smaller, faster DEs and OLBs. Plus, it will improve his ability to block FGs and catch TDs as a situational TE.