It all depends on you efficiency but that above would be about a 20lt recipe. It's a solid recipe but I'd add 200g of flaked oats and 200g of flaked wheat to that too just to round it out. Maybe even consider some citrus zest at the end of the boil?
[Cue - classic Aussie white male sipping a Tooheys New in a Central Coast pub]
"What are you talking about mate? They all taste the same! I can't stomach a VB though, New is leagues ahead"
Jmcl, have you done many BIAB brews before? Are you after direction on how to start and what volumes to use or a particular wheat beer you like? I've done an Aussie wheat which is similar to Redback but like all things brewing, wheat beer has some technique to it that Les could elaborate on much better than I. For starters, I'll skip temperature rests and pH and assume a 20l bottling volume...
Heat up 30l of water to 69°C
Insert grain bag
Add 2.1kg wheat malt and 2.1kg of ale malt (Joe White)
Mash temp should be around 65°C. Leave for 60 mins. Stir occasionally.
Remove grain bag and squeeze the life out of it, getting out every last drop
Bring to boil.
Once boiling, add 15g Pride of Ringwood pellets after 10 mins
Boil for 60 mins
Leave for 45 mins for the solids (trub) to settle
Tip as much as you can in a fermenter and try to keep the solids in the kettle. This should give you around 20l of wort at 1.045 as a guess.
Wait until the temp drops to 25°C or below.
Ferment with Wyeast 3068. Pitch the whole fresh packet straight in. Keep the temp between 18-24°C.
Not trying to be precocious, hopefully this will be a good starting point for a half-decent wheat beer.
POR with 3068 seems an odd mix? I would be inclined to go with a nobel hop such as Hallertau or Tettnanger. I suppose the hops are early addition though so the flavours would be secondary to the yeast flavours.