Those are 28A stall motors, so any battery that has a combined mAh*C/1,000 that is equal or greater than 56A (28A * 2) will be fine. Then you need to check whether it'll fit in your tray, accounting some space for your lead wiring. Hobby king has filters for all this, and sells batteries with xt60's.
I hear the accucell s60 is the way to go, and it looks to be ~$30 various sites.
You could get away with 18ga wire if you're not doing any crazy crush stuff or full auto.
I just purchased 2 Fang Revamped 130 2s motors, acrylic spacers for the motors, Aurora Cage, and Out of Darts Insutanto Flywheels. I also have a new microswitch and a 3d Printed switch plate holder.
Now I need something to power this setup that will fit within the stock battery holder. I wanted to purchase the Turnigy Graphene 950mAh 2S 65C xt60 from Out of Darts, but the battery is not in stock there or anywhere that I can tell. What would be the next best battery? If I have to go with an a 3d printed battery cover I can do that as well if it opens up my choices a bit. more. I'm also assuming I want to stick with XT60 plugs on the battery. After I figure out the battery, I also need to settle on a Charger...one that is less than $30 preferably and is easy to understand. I'm already going to be outside my comfort zone with all the soldering I'll need to do. Im assuming 16ga silicone stranded hobby wire will suffice for this build.
I'm not looking to break FPS records with this, but I just want to be a whole lot more fun outside. If this works out, I'll be attempting to my rapidstrike next.