I'd be surprised if onza put 380mm stays on there. They wouldn't be using it to it's full. If i was onza I'd do as follows
1040mm wb
365-370mm stays (24" will fit in there I just measured and if a cnc yoke is used for both seat and chain stays a 24x2.7 will fit at 360)
use a 26 fork so easy to change from 26 to 24 or a mod fork if a 24 would fit in there.
73 Head Angle
+40 BB
And if 24's catch on I hope there could be a chance of 24" koxx XTP