Singapore Airlines - upgrading business to first?

I am flying from Singapore to San Francisco later in the month and am booked in J with Singapore airlines - i wondered if anyone has flown first on SA on this route and if you think the 50,000 miles to upgrade to it would be worth it??
Any idea if and how i can redeem virgin miles to upgrade on SA?
Cheers
Any idea if and how i can redeem virgin miles to upgrade on SA?
Cheers