You need to find the 5 speed hub with a Narrow axle with 28 spoke holes to fit the 117 wide frame , first ..
there was one , but I dont see it in the current S-A catalog.
Whats wrong with the M6L? I have an M3L with a Schlumpf Mountain drive Crank-set ..
its a wide range gear combo suited for my Hilly Town.
low range uses the BSR gears twice.. ( 54:15 chain drive combo)