You don't need a 502B; the 302B, which I own is better regarded overall. It uses EL34 power tubes, which are nicer and more refined than the 6550 used in the 502B. I believe that the iron is the same, so much so that there are modifiers out there who will modify a 302 to run on either EL34 or 6550 power tubes.
I had a 202B also, I liked the art deco look of the transformer covers. I began with a 102B also; nice little amp.