If he got the original Coca Cola tank and changed it into a real gas tank.
Put fenders on it like the bike came with and get a 50s style front fender light that would be a way cool bike
He's got the chain guard and seat at least he should paint Coca Cola on the gas tank and get chrome fenders, that would be close enough to Cool, but only If he does something with that muffler like run it out the back and put a coke can on the end