The 4 vantec fans and the papst fan arrived.
I’ve taken the 60mm fan out of the power supply and have test fitted an 80mm fan in its place. It appears that the 80mm fan will fit inside the enclosure without any real problems.
The only ‘trick’ is going to be enlarging the opening enough to get reasonable airflow. I’m going to have to borrow a dremel tool and see if I can do that. All I was able to accomplish tonight was to get two of the mounting holes drilled. I started to cut the opening by hand, but soon gave up on that.