well I would always use a mat with a photo framed under glass, the direct contact between frame and glass is generally not good even for relatively short term use. If you are going to have to get custom mats cut then you could just go with taking them to standard print sizes. If you want to match a print size to the frame then Whitewall will do prints at any size you want. They generally print up to 72" wide and about 110" long IIRC, although it does of course vary with each different paper type. It seems that there is no generally standardised paper roll widths for photo printing papers. The only possible drawback with Whitewall is that they are not at the budget end of the market, quite the opposite actually, still the quality of their work is second to none in my experience.