filtration Help

I bought a tank sight unseen and was told it was complete including filters and all required hookups. I had little choice but to trust the seller as I could not personally afford to make the trip to go get it. I was told it was a 175 Gallon tank but it turns out to be a 110 Gallon Tank. it is 3 ft tall 50" long and has been drilled in the bottom for bulkhead fittings. I have the bulkheads but that was it no filter or lights or anything just tank and stand. I still got a good deal but now I need to setup a filter system. as it is drilled I doubt I will be able to go with a wet dry sump but I will need some advice on a filter system. I am sticking a 12" silver Arowana and a reticulated Ray as well as maybe a couple other social fish How much filtration do I need and What should I use? I am fairly Handy and so DIY is an option just need some guidance. Thanks in Advance (long term plan is to build a 500G before Christmas)

well the 2 drilled hols are in the middle of the tank so it would look kinda odd having it running to the top of the tank wouldnt it I am open to suggestions though

Middle Bottom

cool is a 20G sump big enough? or do I need 30 or more I have a spare 20 and 30G tanks right now I can use