http://www.nfl.com/player/darylgardener/2500759/profile
Looks like Gardener was 295 last time he played, per nfl.com. A quick google search has him as heavy as 330 or so during his stay with Miami, but it doesn't specify if that was his playing weight or if that was just the heaviest he weighed in at. Wilfork is listed at 325 and he plays DT in NE's 4-3 alignment without issues. I don't see why anyone would expect Soliai to have issues with it, especially considering how often he did so last year...
Gardener was definitely well above 300. All people talked about was the combined weight of Timbo and Gardener, and how nobody could move them. He weighed 295 when he attempted a comeback after 2 back surgeries. He wasnt on the Fins at that point.