Joined: Sep 2008
Posts: 1,787
Likes: 350
From: Tepic, Nayarit, Mexico
Bikes: 48 Automoto, 49 Stallard, 50 Rotrax, 62 Jack Taylor, 67 Atala, 68 Lejeune, 72-74-75 Motobecanes, 73 RIH, 71 Zieleman, 74 Raleigh, 78 Windsor, 83 Messina (Villata), 84 Brazzo (Losa), 85 Davidson, 90 Diamondback, 92 Kestrel
Henry III is/was making long cages specifically to fit a Campagnolo NR/SR rear derailleur. That would allow you to use an even bigger freewheel like 32 or 34 teeth. Look for his recent post in the For Sale thread.
But first try a 28t FW, it will make a huge difference from a 23t, maybe enough. 42-23 is insane for the mountains.