Since I'm out of school, I decided to fool around with a really old 1965 sears-branded puch frame that's been in my basement forever. After trying to jam every spare wheel I have onto it, I went to find the rusty old turds that came on it originally, and discovered that they're 650's. I don't mind this because I'm a small guy (5'5"), but I originally wanted to do something goofy with this frame for fun, like build it up with some fat slicks and a coaster brake, but the spacing on the dropouts really limits my options.

So, does anyone have any suggestions as to different ways I could build up this frame?
(without spending a buttload)