First off, your existing tank looks amazing. Very good use space. I have huge respect for people who can pull that off with a smaller tank. But I was thinking about your new tank dimensions. My 77 is 16" front to back and I struggle with aquascaping to find a sweet spot between placing rock work and leaving enough negative space for glass cleaning and visual appeal. If the space you want to put your tank allows for it, you might consider a bit wider tank.
You mention that you want to use your existing T5 lighting and are concerned it may not be enough for a larger tank. If you went with an 18"-24" tank and put your rock work either centered or a bit back of centre, then mounted your light right above it, that would give you nice visual negative space with your rock work highlighted by the light. Place all your high light requirement corals on it, and low light or non-photosynthetic corals on the sand bed, (like dendro's, gorgs, or blasto's)
Then when finances become available, you can upgrade the light and you've still got a really nice dimension tank.

Thanks for the input everyone :)

So since the only problem was the tank was too "shallow" and the width was very "limited". So I decided on a new dimension:

40" X 20" X 20" = 70 gallon!!!!!!!

Thanks to Dave and Denny for helping me decide on the dimension by explaining stuffs for hours! And I have placed the order with concept :mrgreen: So now I am in the concept team too :D

Here's the details:

40"x20"x20"
starfire front (and possibly two side; can't remember what Dave said :P)
external overflow centered on back panel
2x returns
built on foam base
full acrylic on back panel
clear silicon
trim (since non polish)
eurobraced (not single glass)

I am excited :D

So much for poor student. Haha

No really, awesome. I love the set up stage:)

The deal was student friendly :mrgreen:

You'll be happy my concepts tank is siting on my living room floor half full and it looks so bad ass

Half full or half empty? :razz:

Awesome man! Congrats. Glad to hear those dimensions. Expectin' pics soon :D

Thanks :D Yah the dimensions are pretty neat :D I am hoping to pull off some good aquascaping with it. Lets see how things go :)

looking forward to seeing you stock this new puppy . Do you have a timeline target before its wet ?

Not really. I will just go with the flow like gather the equipment slowly and things like that :) 60 gallon and a sump (possibly 20 gallon) is going to be a lot of water for me so I haven't set any timeline. If possible, I will go really fast (like my 20L) or go really slow. Let's see how things are in favor :D

And stocking? Man this is going to have crazy stocking! FISH FISH AND MORE FISH! Corals of course but I will take corals slowly but I am aiming for lots of fish. Hint: I have 7 fishes in 20L; do the math ;)