Those look fine. Just as a point of clarification, if you're doing pt/pd, whether from in-camera originals or enlarged (digitally or traditionally) images, you'll need a NEGATIVE, not a positive. Actually, the 6x17 size/proportion isn't that problematic for contact printing frames, if you have the right frame. I have a vintage (1920s/30s) 12x20 contact printing frame that would be just fine for making prints of that proportion, and I also have a similar vintage 14x17 frame in which I could do two at a time. But vacuum frames are nice, if you can find one you can afford and have space for it.