Beautiful bird!!
Thanks so much everyone for the advice! Got it imperfect but to my satisfaction. Will post completed pics!
I sealed everything well with XF-86, sanded down with Tamiya sponge sandpaper 3000, and used a Tamiya panel line accent (black) diluted with white spirit. Specifically I used a wacky "finger rub" method, pre-moisting surface with spirit, adding some of the accent, and then quickly spreading it around a ~5cm^2 area with a finger or palm before it settled into one spot. As a result the accent was mostly trapped in the fine panels, and the rest made a nice shading I was looking for as well (the non-factory Tu-160s span a wide range of dirtiness!).
My last hurdle is painting canopy - I've used regular painters tape but have been plagued with peeling paint. Any pro tips beyond washing it down with soap beforehand?
Cheers!