A larger tank does require a bit more of almost everything so keep this in mind..
So, I think you have 390 watts at 3 x (2x65w). Is this correct? I would think you may need only one or two of these strips at most.
Suspending the fixtures so they can be raised/lowered as desired will also help in the future........
Light is what drives plant growth and c02 and nutrient demand. The more light the more demand. Easier to supply a lower amount of c02 when starting out.
A lot depends on your goals and the species of fish and plants kept. What are your goals? Do you want a lot of growth or not? Many fish or just a few? Stem plants or no?
Eheims are great filters but tend to be rated optimistically (like most canisters). Adding another filter will never really hurt but I think you have enough now
You can always add another one..
Is the tank bottom drilled or not? If so, you can have a nice closed loop system and plumb it all together so it is hidden.
A Koralia II or III model powerhead will help with flow and current to wash away waste products and provide nutrients to all plant sections......
I would use either a large DIY reactor (or two one on each side) powered by a 300-500 gph (or smaller if using 2) or possibly a needle wheel/mist setup which then allows you to step down to a Koralia I or II only to help push the mist output around the tank. Since the needle wheel is already a powerhead, it allows for more flow.
8-10 hours duration is fine for your lights. No need really for more.
C02 can come on 90 minutes PRIOR to lights on. C02 can go off 45-60 minutes PRIOR to lights off. Pointing a powerhead at the surface to create a nice ripple will help add 02 to the water and alleviate any stress from playing with the c02...........I have a small Koralia 24/7 that does this to provide surface ripple in my 180.
You can always add more light if the growth is too slow..
I had excellent slow/full growth using 240 watts of t12 lighting over my 180 and using an AM1000 reactor. Mostly crypts, anubias, java, moss, etc. Your PC will be fine.
C02 will be your biggest issue going forward. Think about maintenance too and how much time you will have to give the tank. An easy way to make your weekly water changes will be huge or they get neglected.
As the tank cycles and matures, you will see how it does and react accordingly. Best of luck.
Hope this helps.