QTR-Quadtone RIP

I have mixed my own set of carbon-based inks. To calibrate them I only have a cheap 11 step gray target and desktop scanner. I have made a curve that prints and then scans with the same final values as the target. I have done this using a Photoshop curve in the Gray Curve/Curve setting of the Curve Creator and have avoided providing any linearisation data. I thought I would leave the linearisation section in case I ever find someone who can help me take actual density/lightness readings.

The curve matches the target well, but it is way too dark in photos. I have fixed this by setting the Gray Curve/Gamma setting in the Curve Creator to 1.8 (not is the Advanced Adjustments printing section). 

My questions are: Is this the correct way to adjust if the curve is too dark? If I do get density/lightness readings to linearise with, will this process cause QTR to attempt to return my curves to their pre-gamma, too-dark state? How can I linearise a curve with an intended Grey Curve/Gamma setting of 1.8? Am I missing something?

Cheers,
Nigel.

Just an update.

After questionable assistance from the manufacturer I took my poorly printed 11-zone unknown wonder (from Perfect-Pixs) back to the shop and exchanged it for a Kodak Q13 (even though they are expensive here in OZ). Using the Q13 my results are much better and I am much happier now.

Just one quick question: What is considered a good D-max? According to the Q13, my current setup has a D-max between 1.6 and 1.65 on Hahnemuehle Photo Rag. It looks nice, but I'm not sure if it is a good result without anything to compare it to.

As a side-note, I found that when I scanned the Q13 with my scanner and no colour correction, opened the file in PS and converted to 16-bit Lab format the L values were almost identical to the predicted Lab L values derived from Kodak's reported densities for all patches except the 1.95 density patch. The scanner is built into my cheap multifunction Epson TX650.