The Avalon Trail starts out climbing moderately to the A-Z junction. From there it goes up a very steep section, albeit with nice steps. This lasts just about until you can’t stand it any more, then it levels out and passes Mt. Avalon’s summit side trail. From there it’s a very nice walk across a small ridgecrest and into a shallow sag, before another moderate but not bad climb up to the Field summit. From there it’s an easy walk (not unlike Starr King to Waumbek) over to Willey.
Take your time on that first stretch and I think you’ll be fine. Bring plenty of water, there’s none up there.