Two fans will be better than one for cooling your processor. By looking at the two products they appear to have the same model of fan attached to them but not the exact same design when it comes to the clips.
Its likely that the fans off of the V6GT will fit on the T4's heatsink but I can't be sure.
Maybe watching this video will answer some of your questions and give you an idea on dimensions:
https://youtu.be/tuwpWGmDLsE