I’ve done it twice, first time in the race.
It is fucking steep. In the race i rode 39/27 and was fair cooked already. The second time i did it on 39/25 and was much fresher. I just made it up. This was some years ago when I was considerably stronger. It is doable, but you won’t do it on a single speed in my opinion.
When you descend stop a few times to cool your rims down - make sure you do it.
Drive to Noojee: up to Baw Baw and back is about 100km return trip through some really beautiful countryside. Then have a pint and a burger at the pub in Noojee. It’s a fantastic day out. Just be prepared.