91.509 Survival Equipment for Overwater Operations
(a) No person may takeoff an airplane for a flight over water more than 50 nautical miles from the nearest shore unless that airplane is equipped with a life preserver or an approved flotation means for each occupant of the airplane.
(b) No person may takeoff an airplane for a flight over water more than 30 minutes flying time or 100 nautical miles from the nearest shore unless it has on board the following survival equipment:
(1) A life preserver, equipped with an approved survivor locator light, for each
occupant of the airplane.
(2) Enough life rafts (each equipped with an approved survival locator light) of a rated capacity and buoyancy to accommodate the occupants of the airplane.
(3) At least one pyrotechnic signaling device for each life raft.
(4) One self-buoyant, water resistant, portable emergency radio signaling device that is capable of transmission on the appropriate emergency frequency or frequencies and not dependent upon the airplane power supply.
(5) A lifeline stored in accordance with Section 25.1411(g) of the CASRs.
Nothing particular there about glide range though.
However, if you are operating under Part 135 you can't just decide "this will be a Part 91 flight". You are either on a Part 135 AOC or you are not and all operations must therefore be conducted in line with the CASR 135 and any applicable Operations Specifications.