Keith:

The low needle will be close when it's flush, but no matter how rich or lean the low speed is it wont keep you from peaking the high speed.

And as I said, you can't always see a broken valve springwithout taking it out to check. But since you're getting almost 7K rpm, it is far more likely the mixture that is killing your high speed.

Another possibility is the cam timing. Has the engine been taken apart? Could have been reassembled with the cam timing a tooth off.

Bill.