You guys will save some mileage if you do this as a linear with cars at either end.
We did this in June, I think it saved around 5 miles of walking. The only dodgy bit is the railway line, where you'll need to take the boots off to wade through the underpass, or chance it nipping over the tracks into the forest. Park one car at Glen Lochay and the other at Dalrigh.
PS, doesn't save you any ascent