So my dad over the last few years has really gotten into bicycles. He likes the older type, like Schwinn cruiser style. He has even bought a Schwinn Black Phantom, which looking at them online, are pretty valuable. He has been talking about getting a gas bicycle kit to put on one of these bikes. I would like to get him one of these kits for Christmas but I do not know nothing about them. Anybody know of a good place to get these and what I should be looking for? I don't know anything about what engine size he would need or nothing of that nature. Any help would be great! Thanks!