The good news, that's a fairly clean setup. Not a lot of homemade custom parts it looks like. That long-spring saddle might be difficult though. It looks like a rare piece to me, but I could be wrong. Anyway, most of the ads on the side of the page are vendors who sell motor kits. The front forks are what are called springer forks, and Venice Motor Bikes carries them with a disc brake setup for around $200. Alternatively, www.bikebuyers.com
also carries a less expensive non-disc brake version for around $35. I do not know what that gas tank came off of, but ebay has plenty of used gas tanks for sale. I do not know exactly what bike that is, but the frame style is called a beach cruiser. I bought my cruiser frame at walmart and upgraded some of the parts.