I want to take an old friend of mine to prom, but we're not close anymore?

Hi so I'm a senior and my friend is a sophomore. I would be taking him as a friend, I'm not looking to date him. But hey, if things work out that way in the future, cool. But as of now I'm not looking at him that way. Anyway, we are neighbors, we were really good friends when I was little. There was a girl who lived in between our houses but she moved away when I was in 5th grade. Her move and me going into Jr. high and growing up kinda made us drift apart. We still talk once in a while, say hi, but it's a little awkward and I also kind of miss being friends with him. He even had a major crush on me for years, but of course we were just kids and the age difference was a lot bigger. Is there any ideas of how to reconnect? Do you think he might say yes even if you don't know him?

Please don't tell me I don't need a date, I know I can have fun without one, but that's something I want to look back on and smile :) even if it's just a friend!

I was thinking I could gather a bunch of pictures of us from those days and put in on a banner. But, how would I get the "as friends" across without making it awkward?

Also, any other cool promposal ideas?

Thanks! :)

PS: My theme is the great gatsby, I know that doesn't matter but I thought you might be curious :)