Hmm, so I paid insufficient heed to chain length and the amount of play the Eno was able to take up (its range is limited by wheel clearance on the seat tube). Looks like a 42T ring with the 18T cog would use the same number of links as 46x16, so I'll try and pick one up. Sixty two gear inches will still be good for climbing. Triple stack bolts were fine, by the way, so no need for extra long ones.