Switching from photo black to matte black

[doggles]

Does anyone have any experience of permanently switching from Photo black to Matte black ink on the 2100?

We have got several hundred (pen and wash artwork) images lovingly balanced so they print ok but after three years we noticed that for some reason (lost in the mists of time), we had been using Photo black ink with Archival/Enhanced Matte paper.

Has anyone had any experience of switching blacks (photo to matte) and getting their older prints to stay looking the same?

We are mainly printing artwork at the moment but would like to print photos from the same printer and the matte black would really help, as we want to stick with the archival matte papers.  We don't want to switch inks back and forth all the time.  Or is there no easy way to do this without making all of our old prints looks very dark?

I guess I'm hoping a simple curves/levels adjustment could counter for the stronger blacks without altering the rest of the image?  Life is never that simple though.

Ian Moody