I'm pretty sure the bottom fan hole can support a 140mm fan (or 14cm)
When I had my 120mm fan in the bottom of mine, it had 4 larger screw holes besides the 120mm mounts.
That said, you should just get 120mm fans. There is hardly any difference between the 2. There are far more options in the 120mm field then the 140mm field. And they are cheaper too.
Just my two.