Can I ask what your goals are for the tank? This will help decide if the array will fit your needs. You have a good start, but it may need a little tweaking.
You mentioned that you are looking to replace 2 T5s, but don't state wattage. Also you haven't stated your tank dimentions. This info will help shape things.
Epic, thanks for the plug
Currently I have 1 65W 10000K T5 per 22 gallon tank. It is about 3 WPG but not sure if that is the right way to measure. My tanks are 24" L X 15" W X 18" deep.
The light bars are 8" inches above the tank surface and the average depth of substrate is about 2.5 to 3 inches". So I did my calculations of the light spread at the substrate for a depth of 8" + (18" - 3") = 23". I actually calculated for 22" just to account for slopes.
I am doing my own calculations to determine PAR at the bottom but they will be highly approximated. Please suggest liberally
Let me know if I am missing any other information.