The weight (LW/TOW) of the aircraft determines the length of runway it needs, i.e. a B737-800 fully loaded with passengers and fuel needs a significantly longer runway that a B737-800 with just a couple of posh tarts aboard.
6000' should be a long enough runway, regardless of exec jets most (lightly) laden) airliners should be able to get in and out on that, just look at what Bristol Lulsgate achieves with just 6,598' and they go in/out, perhaps, fully loaded there!