In Super Mario All-Stars
, the text data is located at SNES address $15E861 or so. That means PC address xAEA61. (Headered ROM.) It's in stripe image format, which is a format explained in a thread in the Tutorials forum.
I wish you hacked SMB2:SMAS however, because with NES, I really don't know, so I'm not 100% sure if what I'm going to tell next is going to be 100% true. However, if the data is in the same area as in SMB2 SMAS (unfortunately, I doubt this), it'd be located at PC address x26871 (according to Ersan, NES ROMs have $10 header bytes instead of SNES's $200). Don't get me on NES addresses, I have no idea how those are calculated.
There's also a possibility NES uses an entirely different way to upload those tiles, so heh...
Don't follow "Find Roy's Dignity", my hack
. Because it's pretty outdated. <--------