If you want a manual, go for the Clubby, you'll be much happier with it. As great as the Grange is, if you can't stand auto transmissions, you're just not gonna be happy. The R8 is also gonna be easier to drive, and to park, since its got a shorter wheelbase than the Grange.
As for me, personally I'd go for the Grange.
I just think they're a damn sweet car
For the record, Y Series never had a 6L, either you got the Y series mixed up with the Z series (which DID come out with the LS2, at least in HSV form, anyway, while the standard Holdens retained the 5.7L LS1) or the salesperson is wrong.
I can understand a LS2'd VZ being faster than a VE though, isn't the VE supposed to be about 100 or so kg heavier than the VZ?