if i had 350 gal, i would make a good sturdy divider, maybe out of some opaque plexi glass... and divide it... get yourself 2 fahakas!!!!!! the more the marrier! that would make 175 gals for each side. still PLENTY of room. Or maybe an arowana, i read they need about 125 gals as well, so still enough room for one.... or, what else, some HUGE angel fish? that would be cool.
youd probably have to drill holes in the plexi glass for water flow, and maybe attach them with some heavy duty suction cups (thats what i did with my dividers) you have to replace the suction cups like every 6mo for them to stay strong, but they are cheap... anyway, thats what id do, it would be sweeetttt....
PS- congrats on your fahaka, hope it arives healthy and well.
EDIT: i just remembered, there is a place by me that regularly carries fahakas, they have 2 at the moment, and are almost always in stock... they are babies, about 2 inches... they are only $24... i bet if you divided the tank, and really wanted another one, we could probably work something out and i can ship it to you... bet it would be less than 70 bucks all together
just a thought...
oh god! DONT DO IT! i had no idea... now i feel like an idiot 
we are going mbu the nice lady on aqaubid gace me a refund before shipping and my wife wanted a MBU instead...(and if she is on board that means bigger tank,) I have already plumbed in enough filtration capabilities for over 5000 gallons and I spoke with my glass company who buildsthe tanks for all the bass pro shops and they would build me one in my home at cost when i get ready to do so really very cheap...ofcours i build my own stands as well ...I still have to get you guyssome pics up... 
