Digital BW, The Print

I need a B&W solution for printing on glossy material. Recently I tried 
some third party inks made by OCP (German?) in a spare Epson C120 
printer with refillable cartridges from inkjetcarts.us. The ink is made 
for refilling  HP 59 /100 gray cartridges.

Quadtone QTR does not support Epson C120 so I have to fine tune the 
prints via Photoshop. It is not as flexiable as QTR but can be done.

The refillable cartridges are bought from inkjetcarts.us. I bought two 
sets to be sure at least one set is working. It was a correct decision 
because the first set was damaged. The second set works but if there is 
a better choice I would choose the other type of refillable cartridges. 
This kind of cartridges from inkjetcrts.us has to be putting or taken 
out of printer at the same time as a whole set just like a CISS setup. 
If one does not work I guess the whole set is gone. Not a really 
flexible design and not recommended. But I cannot find other C120 
refillable cartridges - if anyone has a good lead please let me know.

Epson C120 is a CMYK 4 color printer. The clone (OCP) ink for HP  gray 
cartridges has only three shades. I  mixed two weaker gray  as a new 
shade. So  K position gets the Black ink, Cyan position gets dark gray, 
Magenta  position gets  (1/2 dark gray + 1/2 light gray). Yellow 
position gets light gray. The 21 step wedges printout is in a good order 
from black to white other than I cannot get a deep black after play 
around the settings like photoshop level, contrast, or change to Dot 
Gain 30%. Finally I darkened the printout by moving Photoshop level bar 
(mid value) to 0.65 as a final acceptable working setting. Still it 
leaves a lot to be desired. I really liked Image Specialist/MIS/...'s 
Ebony matte back ink.

My question is: can I use Ebony as black and make three gray ink as 
following:

Black position:     matte black ink from image specialist (Ebony from MIS)
Cyan position:   dye black (OCP)
Magenta position:   dark gray (OCP)
Yellow position:  light gray (OCP)

Will MIS Ebony matte black ink mixed with dye gray ink cause any problem?

- Philip