You should get about 20 PAR with 8 strips, but having 4 at the front and 4 at the back, to make up the 8 strips, complicates things. I'm not sure with them separated that far apart that you would get what I got with them side by side. If you had 5 at each side, that should give you about 20% more PAR or about 25 PAR, again with the uncertainty of having them so widely separated.
If you use 5630 LEDs instead of the 5050 LEDs, you should get about twice that much light. So, I think I would start with about 3 rows across the front and 3 across the back, of 5630 LEDs. Measure the light you get, and add another row or two if you need more PAR.
The biggest problem you will have is the horrendous glare from the LEDs shining through the front "glass" of the tank. For that reason alone I wouldn't even consider doing it this way.