The VL is actuall quite different - its the same floorpan, but front guards, rear quarter and C pillars are different.
I ended up finding this blueprint last night, was hoping for a higher resolution one - ended up finding this:
That blueprint looks much better, and has a vastly greater resolution. It also seems to include the Opel only 2 door coupe. Add a Holden nose to it and you have yourself a VB Monaro
As for the VL thing, I was aware that the fenders forward, rear section and windows are different, my point was that I would remodel those parts of your VL into those of the VB, as opposed to starting from scratch. Starting from scratch would just be more work, and it also means that what in real life is identical between VL and VB (it's more evident with the engine bay/underside/suspension) would be different between your model.