That's the recipe for 5-1-1 not gritty mix. They are definitely different.

For 5-1-1 you need 5parts pine bark fines, 1 part peat, and 1 part perlite. Those are all pretty easily available in garden centers or landscape suppliers. It is not all that different from a fairly standard commercial nursery mix which is 2-1-1 of the same ingredients. It just drains faster and holds less water.

The gritty mix is an aggregate medium. It is equal parts bark, gravel, and turface (calcined clay). Here the principle is more important than the individual ingredients. You could use just gravel if you wanted, you would just have to water more frequently. So if you wanted to reduce that you would add calcined clay or calcined DE.

A replacement for peat is coir. Vermiculite is expensive and most people around here tend to avoid it.

Also, most people refer to sphagnum peat moss as just peat to distinguish it from sphagnum moss which is used with orchids and hanging baskets. Spagnum moss is the stuff on top of the peat bog and is typically long tan strands of moss. Whereas peat is the decomposed sphagnum moss under the living layer in the bog. It is the fine dark stuff you find in large compressed bales.

See!
I knew I was confused.
Thank you very much for the clarification.
Do the substitutions I've collected work as I've listed them?

Moisture retentive aggregate:

turface, oil dry, napa 8822, optisorb, expanded shale

Aeration aggregate:

perlite, pumice, scoria, growstone

Bulk Density aggregate:
Gravel, gran-i-grit, scoria

Got'cha!
Thank you for putting this in.