modifications available to heat zone kit?

when we had our northstar ZC fireplace installed, we had heat zone kit installed and ducted straight down to the basement (8ft run).

in the basement, the duct comes in where an old fireplace box was installed, but that we had ripped out. the concrete foundation walls make a jog to fit the existing fireplace. originally, i had thought of just finishing off the wall flush with the other walls (removing the jog) and then having the heat zone duct vent through the wall. now, i'm thinking that it would be better to save the jog in the wall and frame it out for something else (bookshelves, etc).

my question is: how easy, or is it possible, to reconfigure the heat zone kit such that it acts as a ceiling supply vent?

see pics. ignore all the mess
thanks.

yes, i think b-vent is used for the duct.

i feel like it takes awhile for the length of the duct to heat up meaningfully enough to kick out warm air down low. perhaps if i spray foam it with CCF, when i do my basement insulation project, that might help. is that okay?

followup question to my original question:

i'm now considering simply removing the heat zone kit altogether back to the fireplace (assuming i can get to it...). if i do this, is there anything i need to do to the northstar unit to block off the opening used for the HZ kit? is it just a damper there that opens when the HZ kit is turned on, but otherwise stays shut?

the reason to remove the HZ kit is that i might finish off the alcove as a recessed wall which would allow for a tv to be placed there and out of the way of future rambunctious kids.