Just found this TV calculator. Very handy to know if the PPI will be too large or too small.
http://tvcalculator.com
And it shows the PPI on a UHD 40" display is about 10% higher than the LP3065. Therefore, everything should looks about 10% smaller at native resolution.
View attachment 738560
This 110 PPI is very close to the 27" ACD (109 PPI by the same calculator). If you are OK with the 27" ACD's text size (which in my own situation is a bit too small, because my view point is a bit more than 2' away from the monitor), then 40" UHD at native resolution should be a pretty good choice indeed.