Well incase anyone with a similar question is reading, from my research it seems to not matter at all. Top mounted PSUs have done the same thing for the longest time before bottom mounted came into play. They all drew 'warmer' air from the incase and exhausted it. The original idea of a PSU fan was to pull air out of the case as processors became more powerful since there were no case fans or even CPU fans.
We all know heat rises so top mounted PSUs would actually be sucking out much hotter air than bottom mounted (fan facing up) PSUs.
From tests done on this topic there's hardly a difference in CPU temperature. The theory that the life of the PSU will be shortened from pulling in warm air seems to not make much sense either since it's bottom mounted and heat rises.
It seems to just come down to good airflow in the case.
upside down bottom mount it is.