I don't know how this would work, really.
I haven't seen anything that makes me believe he has the frame to put on another 25 pounds. He ran a 4.55 at the Combine at 220lbs, with many thinking it was on the slow side because he put on too muscle. He's only 6'0, which means he doesn't have any height advantage at all and that he would be one of the smallest TEs in the league. He can't really block as well as you'd like out of your tight end, which is pretty logical, being a WR and all for most of his career.
His strength has always been that he's an athlete. A guy you can rotate between slot receiver, scat back, special teamer and returner. You lose all of that if you force him to put on a big amount of weight. And in the end you'll be stuck with a not-very-good tight end.
Tight ends who are mismatches are just that because they're too big and tall to be covered by corners, but too fast and athletic to be covered by linebackers. They're freaks of nature, rather than guys who are build like wide receivers, but just put on another 40 pounds.