TurboPrint & PrintFab

So here's a project! I'm proposing setting up a Canon IP8700 to run graded grey inks in a dedicated print head for printing monochrome photos - a little like is sometimes done with various Epson printers but with the advantage of being able to easily swap out the printheads so that a single printer can be set up for either Colour or B&W. Intend using Canon GI 61 black in the black pigment channel and GI-55 black in the photoblack channel in refillable ARC cartridges. Another refillable cartridge filled with Canon GI-63 GY grey ink is proposed for the grey channel, with the Yellow, Cyan and Magenta channels being populated with greys diluted and/or blended using the above inks and a clear carrier made from 93% deionized water, 5% glycol and 2% isopropyl alcohol (with about 0.25% Benzalkonium Chloride as preservative). Density checks will be undertaken using a Colormunki in spectrometer mode to read a monochrome step chart with Argyll CMS (spotread -d) and final tuning with Turboprint's ink control software. Has anybody attempted something like this? - and if so, are there any suggestions regarding starting ink blend proportions for the Y/ C/M (now graded grey) channels?

I'm sure I'm not the first to try this ....

TIA for any suggestions.

P.S. - after further investigation, a couple of changes to my proposal above - neutral carrier now 80% water : 20% propylene glycol with no or any IPA determined experimentally - and the use of the above inks changed to a range of dilutions (with the neutral carrier) of Canon GI-63 BK (to reduce potential risk of metamerism) - just in case somebody was about to suggest that ....