Interesting, as in it is the the old argument of the 1911 M1A1 and the 1911 M1A2 (I might be getting the designations wrong, it might be 1911 M1 vs. the 1911 M1A1), where the argument was about the safeties of the weapon. As is, some people at the time were worried about it the palm pressed trigger lock, stating that if the gun as dropped that it would go off. The government tested that by having the gun roll around in a spinning barrel with a dummy load and the hammer cocked back. It rolled in that rest for 4 months, and it went off towards the end of the test when the palm lock got damaged from rolling around in a barrel for so long. None the less, Browning added the extra safeties to the 1911.
 
To date, there is no report of a 1911 firing when it was dropped.
 
It would not take much to convert the Model 80 back to  Model 70. Parts were interchangeable between the two, thus there were hybrids floating around WWII and Korean War of the to guns.
 
 
Edit: It's the M1911 and the M1911 A1
https://en.wikipedia.org/wiki/File:M1911_and_M1911A1_pistols.JPG
 
Edit 2: And you're right, these are much later changes made to the gun.
https://en.wikipedia.org/wiki/M1911_pistol#Civilian_models