The original ceiling heater registers are definitely original - and have been painted over several times. Instead of trying to hide the register from sight, I decided to draw the eyes to them with something more interesting.
For comparison here is the old unit:
Removing the original took some work with a razor blade but, as you can see, several layers of paint still came with it - so some filler will be needed in the future. For the replacement I decided on these units from Decor Grates - an "Oriental" wall unit that has a faux rubbed bronze look. They are fairly inexpensive and not particularly sturdy for foot traffic, but a ceiling location would work just fine.