Nope, you get the original fare class.
If using the bid upgrade then no again it's based on original fare class.
You either need to buy business class to begin with or make a fare change to the ticket to change to a business class fare.
Source:
Virgin Australia
From a technical aspect. When a upgrade of any of the above mentioned is successful the e-ticket is not actually reissued and retains the original booking class but instead PNR booking is updated to display Z class. VA's systems are smart enough to recognise that if an eticket has an economy fare type but the booking has a Z fare showing then the pax has been upgraded to business class (therefore allowing business class seat selection/baggage allowances etc).
On the website it'll show something like "Business Cabin - Flex" (indicating that it's still an economy flex fare)
View attachment 304906
The itinerary will then show something like this:
View attachment 304907
Whilst the eticket still shows the economy fare (in this case L):
View attachment 304908