well idling the engine is bad for breakin. just drive it around. no need to idle it. see my posts in the beginner FAQ that is stuck to the top of this forum for more breakin info.
your carb has 3 needles. 1 a highspeed, l2 ow or mixture and an 3 idle screw. the high speed(HS) is the one that sticks up and points at you. it should be about 2.5 turns out from the bottom for the first start and running. this needle only affects the mixture/running when it is about 3/4 or full throttle. then the low speed or mixture handles the low rpm range. you want to lean that one out gradually to get better and faster throttle response and accelleration. the HS is for the top end top speed. the LS needle is the screw that is sideways on the throttle lever arm, (the opposite side of carb where the HS needle is>
the idle is the last screw. that just sets the stop point of the carb opening to set the idle to where you want it. the engine has to be broken in foirst before you can get the perfect idle dialed in. but you can se how it works by turning it and seeing how the carb stays slightly open or closed more.
and the high rpm seems normal unless maybe the clutch is not on right, but i think it is. it takes some rpm just to get the car moving.