Converting a 727-200 modell into a 100.
 

To convert a 1/144 -200 into a -100, you need to remove .83", 21.2 mm forward and aft of the wing. This is six windows forward of the wing, and the last five windows, including the door,aft of the wing.
On the forward right fuselage, keep the 20 windows forward of the over wing exits; remove the .83", 21.2 mm section including the first window and the door. Blank out windows 13 to 18 (of the remaining windows). This is where the new galley door will be.
Rescribe the front cargo door under windows 10-11-12 (of the remaining windows). If the rear cargo door is shown closed, the only scribing involved is the vertical line separating the sliding fillet covering the door opening. Note that the aft part of the wing/fuselage fillet on a -100 is shaped a little differently -- it's a little longer, a little pointier than on the -200
Shorten the central engine inlet 1 mm, and ovalise it... easier said than done, some puttying and sanding will be involved!
Note that the rear tail fillet between the horizontal stabilisers sometimes ends with a navigation light, sometimes with an horizontal antenna.
General dimensions difference between the 727-100/200
Lenght 100´s= 133´2´´ (40.58m) -----lenght 200´s=153´2´´ (46.69m)
wingspan and height remain unchanged.
Dif.  -6.11m/144=42,4mm

 How to modify a 727-200 into a 100

All information taken from the Airline Modeler digest