8 feet only ah 
Mine is 9 feet and I thought it was low. 
I am going ahead, as my original ceiling is not level and looks "wavy".

Do you plan to put a ceiling fan in the plaster ceiling area?
If yes, better don't put up the plaster ceiling.

Not much people using cornice lol, but you may want to consider putting a Dome or ceiling Panel for your fan, which allow 3-4in high for the fan itself.

Also consider what type of downlight the you plan to use, example: If using External box type, than the gap between plaster and ceiling will not require so big. If you decide to use Long type (8 inch) or Vertical type (4 inch) that this will impact on your plaster and ceiling gaps. Because I do the mistake didnt put it into consideration, end up my contractor just open 9inch gaps between it...

You may also want to consider using baby fan which smaller than traditional fan, but I'm not sure is the power or not 

If you add plaster ceiling it will deduct only around 8"
(Low ceiling do not use too big a vertical bulb downlight , so only deduct you around 8" height or you can go for those horizontal bulb downlight, deduct you 6" height).
All in all still have height approx. 8.5'nett. OK lah...
Go for it girl 

Err maybe I put it this way:-

Original ceiling height - 9feet 6inches
Plaster Ceiling - 8 inches (Type of downlight determines your plaster ceiling depth)
After Renovation - "9 feet 6 inches" less "8 inches"  = "8 feet 8 inches"
Conclusion : Ceiling height still higher than "8 feet 6 inches"

OK mah , Lu pergi buat lor