Could I keep an 11 inch Silver Arrowana and lets say an 8-10 inch Jardini together?
And what's the best way to treat drop eye? The left eye on my Silver has it.

You can't keep a silver and jardini in a single tank. Your jardini will kill the silver unless you have a very very big tank and put more arowanas.

How about a Black Arrowana?

I have personally seen a tank with about 6 silvers and 2 jars. All over 2 feet. They stayed segregated but were ok. I have seen online a few times a silver and a black. You'll still run the possibility of aggression with two aros. You can always try it, just keep a close eye on it for as long as you can after you put them together. And with one jar and one silver it's not DEFINITE that the jar will kill the silver, but it is probable that it will happen eventually.

You can keep silver and black together, but you need to watch out for aggression. If you want a perfect barbel, scale and fins I would put 1 aro in a single tank. How big is your tank anyway?

Its only a 75 for now but plans for a 265 are in my near future plans. I would like to get a tank that is about 6 feet long by 3 feet wide but a tank that big won't even fit through my doors.

It will if it's 24" or 30" tall. Just turn it. I have an 8x4x2. Put it on it's BACK and it'll go straight though any door.

Arowanas are typically aggressive towards each other. The way I look at is that it can be successful, but a HUGE tank is needed...at least 300 gallons down the road. Even then, aggression would likely be a problem...if not a problem, there would still be minor fin nips and whatnot.

Arowanas are so beautiful on their own that I always say...if you want a perfect one, keep it by itself! I've always housed them singly and they always grow out flawless.

I agree with dracofish. Put them singly and you'll have a flawless aros.

The only thing I'm worried about mixing aros together or with other fish, is that when someone tried to take a nip on the aros barbels. Juveniles will have no problem growing them back, but at 10" it takes about a 2-4 months. Sometimes it will not grow back or it will grow back not in perfect shape.

I have a 30"+ silver that had NO barbels when I got it home at that size. It took about 2 months for them to grow back.