What's "early"?
If it has the honest real actual sandcast engine cases and they aren't cracked around the sprocket, then it's worth a lot just for them. A lot of early bikes had the cases replaced - with diecast cases of course - when a chain break ruined the cases. Collectors and restorers will pay a good buck for a frame plus a sound engine with correct numbers regardless of the condition. How much "exact to spec" original equipment you have - switchgear, brake hoses, fenders, exhaust... there are a hundred or more oddball "sandcast" parts - and what condition it's all in makes the difference between a $2000.00 bike and a $40,000.00 bike.