IMO, 10 square is the best all-around fitment. It's balanced from a handling point of view, has lots of grip, looks good, and can be rotated.
Largest you can fit up front is a 20x9 according to those I've spoken with, so you're stuck with a 275 max up front. As far as the rear goes, 295 and up only, and 295 is a stretch on an 11" rim.
11's go up front fine....some camber and some other small tweaks are needed though, but nothing serious.
295 on an 11 is about perfect IMO, but I also need the car to turn, so lots of bulge is no bueno