I would put money on a match between the two, blitz or classic. My money would be on Kasparov - even now.
No time for openings study needed; that is, Kasparov doesn't need it.

The recent trash talk about Garry from former student, Hikaru? Stupid and ignorant. Nothing more.

It's hard to accurately judge Kasparov's strength these days. He edged out Nigel Short in blitz, beat LaGrave in a 2 game match and handily dispatched Karpov in recent years but most likely his elo is sub 2800.

The real question is could Kasparov beat the RHP top ten? I doubt it. haha.