Defiantly go Coona Mudgee Lithgow. Two ways through mountains are either via Great Western Highway through Katoomba or via Bells Line. Katoomba brings you into Sydney on the M4 through Penrith. Bells line into Sydney onto the M2 through Richmond. Bells line has more twisty stuff if you are into that. Dunedoo is about half way from Gundi. Couple of cafes and bakeries and I nice park if you want to pull up. Servo too.