go Putty Road, New England Highway (towards Newcastle), Pacific Highway up to about Tea Gardens, then Buckett's Way (towards Gloucester), Thunderbolts Way to Walcha, then New England Highway for the rest.
For a quicker run, head up the F3 and Pacific Highway, then Buckett's / Thunderbolts.
You'll go through some of the best roads you'll find anywhere, and it's about an hour quicker than New England Highway from Sydney to Armidale.