I don't think it will draw the heat well if it doesn't have a flat flush surface. It would be better to just take the fan and mount it so that you can get the hot air away from it, without affecting the airflow of the Case. Good idea though.
Sounds like a great idea, but I been thinking more about it. Honestly, I wouldn't put thermal paste on them, and just sitting them on the hdds might be to much weight on them. You will only be cooling a specific area though. I think a fan blowing air away would be more effective, since the hdd's don't really get the hot anyway.
There are already hard drive cooling fans from manufactures like Thermaltake,scythe,acutake,akasa,prime cooler, zalman and much more... Google it if you don't believe me.
and your 2*80 mm are for the hard drives and the air flow off the case.
Anw i am not mounting the stock cooler on the hhds because the is a serious delay built in the intel coolers of readjusting the rotor + they are very very noisy so it doesn't worth the sound
That's an excellent point from Brett - I'd be very careful to avoid any unnecessary additional vibration around hard disks. Brett and FinneousPJ are also correct that it isn't necessary - hard disks would already have fans if needed. This being said, it is a good idea to make use of extra fans lying around if you don't mind adding a few extra dBs of noise to your machine.
Another possible way to make use of the stock cooler is to sell it - some people will buy OEM CPUs without the cooler yet may be happy with the stock cooler and just looking to save a few quid. There are some high-end Intel CPUs that don't bundle a cooler anyway, and again, buyers may be happy with stock clocks and a stock cooler (that said, I think it's LGA2011 processors so not sure if an LGA1155 cooler would fit the motherboard).