6x17 only needs 179mm; however, 200mm would allow for some movements. With lenses you have lots of choices. 75mm grandagons (f 4.5 and 6.8) would both work. The 75mm offerings from Schneider, Nikon and Fujinon would also work. The grandagon f6.8 will likely be the least expensive choice. A 72mm SA XL would be the widest that has full coverage.