Sorry, 6x8" is actually a proper photographic size - historically. You then move on to 10x8" and 12x8". Obviously inkjet printing is another matter, and it's introduction and widespread useage has corrupted what was considered normal photographic formats.
So far i have only got some ilford A3 smooth pearl. Only had the printer a few weeks so havent ventured to far into paper as yet.
Im starting to think that a Lab might be the way to go for most print sizes .