If you do not mind loose fitting then go with a DH or MX type jersey. You can even give Under Armor (either loose fit or the tight stuff) a try. Since their stuff is made for athelets (other then cyclists) they make larger sizes and their lg, xl, and so forth are actually what they say. Not like cycling where a 3X fits like a med.

If you do most of your ordering on line I find this place has good deals for U.A. clothing.

Eastbay