For your budget of 60K, if you are looking for KEF (or) Dali you may only be able to get only fronts & subwoofer.. Additional cost for center & surrounds...
But for 60K ~ 70K, you can complete a 5.2 (dual subs) system with Taga Platinum series which can be a significant upgrade from your HTIB speakers..
I am looking for fronts for now.