correct filtration for a 220gal tank

My current tank is 55g. I got it back in the early 90s. It's been a
great tank thats served me and my freshwater fish well over the years.

I recently purchased an upgrade for $550. it's a used 220gal tank (7'
long 2' thick). it came with a magnum 350 with the 2 bio wheels, 5
powerheads to keep the water moving, rocks, decorations, heaters, stand
and canopy. really, it has everything need to get it up and running.
But, I have a question or two concerning filtration.

I know the amount of filtration you need depends on the amount of fish
you plan on housing in the tank. but I would rather over filtrate than
under this is what I was thinking of doing, please let me know your
thoughts:


Primary filtration:

2 magnum 350's w/ bio wheels. (this will give the tank a total of 4 bio
wheels)

Secondary filtration:

1 72"x18" Undergravel filter w/ 4 tubes and 4 powerheads.

Planed fish:

1) 1 large oscar
2) 1 large clown knife
3) 2 large tinfoil barbs
4) 2 large bala sharks
5) 1 large sucker mouth cat
6) 4 med clown loach
7) 1 med firemouth

Thank you for your thoughts on my planned setup and fish. BTW, currently
I own the Oscar, clown knife, sucker and firemouth.