I would throw at least 20 gallons of worm castings in a bag that big, and maybe 15 gallons of the manure.
I feel the castings are essential to my mix, they hold water nicely, are full of good stuff, and the plants seem to respond really well to them, with even growth, disease resistance etc...
the more the merrier!
I also use oyster shell and granite dust instead of perlite in my mixes for slow a release calcium, minerals and soil drainage.
Leaf mold, created by piling tree leaves up for a couple summers, can substitute coco or peat moss, and it is not only free, but better than anything in the stores, because of its mineral, fungal and elemental properties, and its ability to hold water like a sponge. (just like an old growth forest floor)