How long is a piece of string??
It really does depend on the amount of work that needs to be done. I'm sure that any of the restorers advertising in MPH would be pleased to expand in detail, but the thing is, you can't really expect them to give you a firm quote at the start, without having had a damned good look at the bike. For example, they won't be able to tell the state of the engine internals until they are in the crankcases I wouldn't have thought. And then it depends on what degree of restoration you want - do you want it perfect, or just rideable, do you want modifications etc etc etc. May I suggest that you contact one or more of the aforementioned specialists.