For the upgrade to work you need Biz award inventory to be available. You can check that yourself using ANA or Aeroplan or even co.com for TG award space rather than calling in. Once you see that available getting the upgrade should be trivial.

I took that flight in C westbound in late July and was rather unimpressed. I didn't like the timing of the meals or the seat comfort in general. Next time I'll likely fly the other direction or just save the miles and slum it in Y.