EMB-175 Captain reported encountering wake turbulence enroute to MIA in trail of a B787.

Narrative

While we were enroute to MIA Airport; ATC advised us of a heavy traffic; 787; that we will follow to our destination. At that time we slowed down to 270 kt. and began to call the Flight Attendant to prepare for landing and advised them of possible wake turbulence due to heavy traffic; so they will finish their duties and stay seated the entire time. When we encountered the wake of the traffic; [it] caused both FAs (Flight Attendant) to be sent off their feet and caused the autopilot to disconnect and climb 600 ft. above our assigned altitude. When we recovered the aircraft and the altitude; I called the FAs to know about their health and they replied they were OK.Cause: We were provided with a short trail in space behind a heavy aircraft and were not provided with sufficient time to slow down to a safe distance taking into account the winds.Solution: Ask for the time of aircraft following sooner and if required; request different altitude or short vector in the arrival due to heavy wake turbulence.