How does the T-Bird feel and handle on gravel/dirt roads and what mods would help to make it a better all-rounder?
It's a street bike. It is not meant to be an "all-rounder." That is what the Tiger is for. I can certainly appreciate that you want a Thunderbird since I own one myself, but let's not try to pretend that the designers ever intended for it to go off-road. Yeah you can do it, but there are better bikes for that purpose.