SF Klein
Senior Retro Guru
You'll have your hands full with that one. To my knowledge, DI2 is a road grouppo; Shimano hasn't adapted it for MTB use (at least they haven't yet). To truly go modern, won't you need to look at a disc brake set up? How will that work with the frame and your existing SID fork? For wheels, what do you have in mind? (something tubeless I'm assuming given the goal of being modern)