"The survey found the worst, most outdated features in homes include linoleum floors (40 percent), popcorn ceilings (29 percent), wood paneling (28 percent), ceramic tile countertops (28 percent), shag carpeting (19 percent) and avocado green appliances (8 percent)."

You would still have to finish ceilings I suppose.  

The church is large building about 2,300 sq ft with tall ceilings 20 ft +.  

He had to remove part of the ceiling and part of a ceiling joist because of some bio matter (teeth mostly) (just shuddered a bit).

Also, prepare to rip out carpets and pads, dropped ceiling tiles if you have them, and do a lot of cleaning, especially around the windows.Since I've gone non-smoking with all my properties, my turnover costs and tenant drama have gone way down. 

Has Owens corning insulation was added to the ceiling and a sound deafening highend cork floor to keep the place peaceful.

Based on my own rehabs I would focus on Painting, Drywall hanging and repair, Vanity installation, laminate/luxury vinyl tile installation, ceiling fan and light installation, baseboard and door trim installation, window installation.

I am repairing the customers ceiling but at the last minute he wanted to fix the roof before the ceiling. 

-Units are same sq ftg (approx 500 sq ft), but one is a studio and one is an actual 1 br-Fully renovated (floor-to-ceiling) units of the same layout and size in the complex are selling today for $155k-$180k (big range, but supply and demand, right?)

If the walls are covered to the ceiling with that stuff then I'd say adjust your offer accordingly.