There is likely no published best glide speed, at least there generally isn't for light twin aircraft. Vyse = Best Rate of Climb Single Engine. It would have the same relationship as best glide in that it will get you the furthest distance on one engine, but it is not aerodynamically related to best glide.
Best glide is the aircrafts minimum drag speed, also found where the tangent line meets the power required curve.
Source 1:
You can see the minimum drag, pointed out here as Vbg
or
pointed out as min drag or L/D max which all are the same thing, best glide.
Source 2:
Pink line shows the tangent line.
Vyse is the speed where there is the greatest gap between power available and power required on in an OEI PaPr curve. Basically, the speed where you have the most excess power when one engine is INOP.
I looked for a Pa Pr curve OEI to show you, but was unable to locate one, sorry.