Here are some 140mm fans tested on a rad and also some 120mm fans on the same rad using a shroud adapter.
Edit: Actually thinking about it it might be possible to use the same adapter in reverse to mount 140mm fans on a 120mm rad, u would lose surface area but with the air being forced into a smaller gain more airflow at a lower RPM, never seen or heard of anyone trying this tho but it could be usefull if u had limited space in a case that has 140mm mounting options.
Edit 2 lol: Forget that the mounting on the rads would need to be spaced out more to get them to fit, only way this could be done is with a 120.1 rad or maybe could be usefull stacking a pair of 120.1 rads to make a single super thick rad.