Update 2/14/2015
I got the motor fired up last night! I was pretty excited about that. I'm glad I went with the aftermarket carb instead of the rebuild kit. It didn't take much to get the motor cleaned out, checked the inside, bolted on the carb, and made the exhaust work for now. I'll figure out how to make it better later.
I also cut a seat pan last night and added some foam from a camping mat. I bought some vinyl this morning, and I ended up with a usable seat cover. I actually made two. I wasn't overly happy with the first. I tried to do the diamond stitch pattern in it, and I just don't feel like the stitches looked good enough. I also like a really snug fitting seat cover, and the second one was way more snug. Now I just need to find a staple gun that I can use to attach the cover.
Up next, I really need to figure out what I'm going to do with this front end. I've been looking at some Chinese pit bike forks pretty seriously. They say they'll fit a crf 50, and I think my wheels would fit that front end without too much trouble. If I could just find a junk pit bike that had the fork and wheels, I'd probably buy the whole thing. That would probably be cheaper than buying new tires, and a fork.