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Do you have the updated valve cover with pegged rocker shafts ?
1300 is a fast idle, 1200 is around normal these days for these engines, 1000 is ideal. If the engine is starting to stall when the clutch is in and 1st gear selected I'd say the clutch is dragging a little. Does the clutch cable run to the left of the engine or the right? if left, check the clutch push rod isn't broken. Grease up the mechanism as well if you have the push rod version, which I suspect you do.
Very long shot but based on my recent experience could it be the kickstart ratchet touching the pinion? This has been confused with primary chain noise in some other threads.