Or Falkirk High - Waverley - South Sub - Falkirk Grahamston? There seem to be junctions facing the right way.I think I can better that : Falkirk High - Croy - Bishopbriggs - Springburn - Cumbernauld- Greenhill Lower Jn - Camelon - Falkirk Grahamston.
You don't have to go into England - see above.
(I'm ignoring the existence of passenger services, just looking at the tracks.)