Seen lots off reviews about the P180/182 case.
They used all sorts off psu's, but i never read anything about bad psu cooling deu to the fan on the upside.
The only problem they complaned about was the fan in front off the psu, which can cause some problems with longer psu's.
I think you should not worry.
Well, this PSU I chose is a bit longer than normal ones...will it fit?