ahh, I see, so the 67 cubic feet is what the mix is for, that's much different.
Gotch, gotcha.
my two cents? maybe ditch the guano for alfa meal, and fish bone meal.
in an outdoor setup you want slow release man, and guanos/blood meals are WAY too water soluble. Especially when you have big-ass containers.
don't let the modest NPK numbers fool you... that guano at 12 percent nitrogen isn't gonna be 12% when it is watered away.
I like the 50/50 mix of native soil, gonna be full of BIMs.
don't forget the aeration though man, you'll need a BUNCH for all that.. and native soil usually is more clay-like than what cannabis likes, course it all depends on where you live, of course.