Well I did mix it up, and made a few adaptations.
I realised that the pre pack of D-19 in the can that made 3.8L of D19 has two bags. A small one held the metol, a bit of sulfite and the hydroquinone. The larger bag held the balance of the sulfite, the carbonate and the bromide.
I measured out 7.6g of metol and 30.4 g of hydroquinone separately and then added them to the solution after adding the pre packaged developers and dissolving them first.
Then in short order after I added the larger bag's contents to make sure the sulfite would protect the excess hydroquinone's activity.
Then once those ingredients were all dissolved, I weighed out and added 205g of sodium carbonate, mono. Actually it was Arm and Hammer washing soda, which I use for home brew developers all the time.
What I ended up after topping off to the final volume of 3.8l is a double the usual stock solution dilution of d-72, with a 1g/L surplus of bromide.
To store this I poured it off into a series of 500mL bottles. It is very slippery, so when it comes time to go to working stregth the stock storage bottle will be rinsed twice as I dilute, and then dilute into a graduate to allow efficient stirring before pouring into a tray.
I will be very happy of all of this works out, because I will have created a warm tone biased Dektol type developer, which is one that I normally use, and came up with 7.6L of stock for the cost of 7g of metol and 40g of hq. I consider arm and hammr almost free, since it comes home from the grocery store, and thus so flies under my wife's photo activity spending radar
If you find yourself tempted to use the washing soda for your carbonate, be warned it has a small perfume agent incorporated that will mostly float to the top and floc up, allowing it to be skimmed off before bottling. It is annoying, but not as annoying as paying Canada Post freight rates on photo grade carbonate.
Thanks for the benzotriazole tip, John. I actally do keep a 1% btz as I think of it in methyl hydrate for just such duties. It has been a few years since I mixed that stock, and since it is an organic antifoggant it is time to dig out that little bottle of fluffy stuff and persuade some to go into a fresh solution again.