Good recap and options... I'd like to keep my bike and have a 28 on the back but the more expensive it gets to accomplish that the cheaper it becomes to put the "Z" back in OEM condition and go for a quick sale at ~$450 ('15 at ~1,700-1800 new) or so and just buy a new alloy (endurance/'gravel') bike with 105 components for <$2K (e.g., perhaps a '18 Domane on sale).