the 28 option works better for both setups as it gives a good half step all the way to the end and doesn't have any duplicate ratios.
I used 28mm 622 because he dropped all 27/635 ERTO wheels
here is the layout of gears from the web,
HTML5 Gear Calculator
I would go with the 49-46 six speed

__________________
72 Geoffery Butler, 72 Gugificatizion Witcomb, 72 Raleigh Gran Sport SS, 74 Raleigh GrandPrix dingle speed, 74 Raleigh international, 81 Centurion Pro-Tour, 85 Gazelle Primeur, 29rBMX, Surley Steamroller 650b