A couple of weeks ago I flew a Cherokee 140 in Italy fully loaded, in fact 15 kgs above MTOW. Outside temperature was 32 C and field elevation 900 feet.
We indeed had a very long tarmac runway and gave it an extra 10 MPH on takeoff roll and seemed to behave quite nicely. I guess the long runway/clearway makes a huge difference though.
I don't have a lot of experience on 140's and I wonder if the unusual instrument layout (compared to the modern T shaped), the MPH airspeed and the absence of an aural stall warner could have played a part ?