For actual bike jerseys
Yep, aerotechdesigns is a good place. I have some their sleeveless jerseys in XXXL that fit pretty well.
I also found a Pearl Izumi style that worked for me in XXL. They, and many other manufactures, make different fits, including loose/big. Unfortunately, I think PI doesn't have that style anymore, but they seem to have a few other styles that are loose fit.
Also, do a thorough search on this board. This has been addressed many times, so there are many other recommendations. It is just tough, as you know, to find actual bike jerseys that fit big guys. I usually have had to mail order and take a chance.
Of course, the other non-bike recommendations might work, but I find that even more hit or miss for me.