There may be different engine variants available for the 727-200.
The stats you see on the Purchase Aircraft screen (the list with the various types of aircraft, eg. 737-400, 737-500, 747-400...) are just for the default plane.
To select a different variant, go to purchase the aircraft as normal. Click Buy button, and you come to a page where you can choose the number of planes you will buy. There will some times be a drop down box under "Engines" (not all aircraft have different engine variants).
In this drop down box, you can select various engines. Different engines will have different ranges, speeds, fuel usages and prices. Most of the time, the default engine is in the middle, with shorter and longer ranged variants available.
E.g.
Boeing 777-300
1- 4465 nm, $247 million
2 - 4660 nm, $250 million
3 (Default) - 6570 nm, $276 million
4 - 6852 nm, $280 million.
Say you wanted to run a route of 6700 nm, Route Research would say the 777-300 works, however the aircraft list would not.
Remember, you can investigate the different engine variants without purchasing (just change the setting in the drop down box, and the page reloads). You can easily save money by using variants with less range but also get extra range on aircraft. I did this with A319s, purchasing ones with 2000 nm range for European flights but over 4000 nm range for trans-Atlantic flights.
