V2 plus 20 KIAS gives you the best L/D ratio on a 737.
Does that assume you are gliding with flaps down since V2 is usually associated with a take off flap setting. I would have thought that any drag systems would increase the glide angle. For dead stick approaches in the 737 Classic we normally use 210 knots clean to reach vicinity of the airfield then flaps 5 and gear as required to fine tune the approach. This is pure "about yea" guesswork and not based on any specific figures from a manual