Not sure why it's flipping the starter and core items around like that, just switch them around and you should be fine.

I've been playing a lot of Mid Lane Shazam on GD and having a lot of success with him. You're going to have a rough time the first few levels, but with the jungle to help put just a small amount of pressure on the lane you will be able to out sustain and poke the enemy mid laner very shortly. 

Mid and late game you become a monster, making it very difficult for anyone to kill you, and more importantly anyone to get away from you. With your Atlantean Royal Seal and your E (which stack multiplicitively not additively), it's almost always a guaranteed kill. When it's not, that's where the Stolen Powers come into play.

I know a lot of people dislike leveling his E and find it useless, but it does a ton of damage and really makes it easy to secure ganks in lane. I honestly don't find his W to be very useful, and level it last. You could even leave it at 0 points if you want. Generally though I will put 1 point into it and stay in the attack stance the whole game. The passive power pen is nice, and you can switch to defense stance after a tower dive to absorb some damage (as the scaling health will still make the shield nice late game at 1 point). 

I like to build him very tanky, making use of his passive. You will have slight energy issues, but once you get Blue Scarab that's no longer an issue. However once I get that item I find I have cooldown issues. So your last item can very well be a big cooldown item, or if you are still getting blown up too easily you can grab more health or a Ra's al Ghul's Robe. If you want to be a team player and are good at remembering to use your items (I am not) Oa Gambit is a very good item. Just make sure you build the second tier of it early and let it sit there all game to generate credits (the credit gen mod would be useful at this point).

I'll edit the rest later once I decide what I like the most for the mods and amps.