There's plenty of options if you're willing to go off-track. Most of the bush in that part of the mountains is reasonably friendly.
A couple points to help with your planning:
1) Parts of the Sassafras Ridge Train and Numantia Falls themselves are on private property. But I believe this is the same landowner whose property is traversed by the upper section of the Victory Track, so I don't think there's any access issues for bushwalkers.
2) The Grose Rd option outlined above will definitely work to link you up from Faulconbridge to Linden (then continuing on fire trails past the wall of Lake Woodford over to Burgess Falls). It does require a lot of plodding along a road though.
3) A route worth considering is to come up the Victory Track, cross the railway line / highway at the level crossing, then head out St Georges Crescent. From here you've got a range of options. The track at the end of Shirlow Ave is an old fire trail that goes all the way down to Linden Creek, which you could then follow for about 1km downstream to join up with the trail on Linden Ridge (I think this is quicker and nicer than Grose Rd). You could also follow the trail at the end of Hillcrest Ave, which takes you to Linden Creek higher up. From here you can follow the ridge on the other side to Linden Ridge (I'd expect a bit of scrub on this ridge). You should also be able to go down to Linden Creek from the end of St Georges Crescent. There's a ridge just west of there (marked here:
http://maps.ozultimate.com/?lat=-33.692 ... 9555988114) which I walked part of and found to be beautiful and open.
T2