I recently bought a bike and the seller offered a "box of bits," too. I gratefully accepted but am a bit confused over one item and wonder if you can help. One of the items is a frame (753 Peugeot), which appears to have a wheel size of 700cc at the back and 650 at the front. Is this possible and what style of cycling would this suit (I am probably going to sell it so wonder who would be the market)?
It sounds to me like you might have purchased a road time trial bike from the 1980s, sometimes referred to as a "funny" bike, due to the smaller front wheel. This name comes from the hot rods called funny cars. The smaller front wheel was said to improve aerodynamics. I'm guessing that that's what the bike is based on the fact it has a Reynolds 753 frame, which is a somewhat rare and expensive tubeset (when it was new).
If it had a regular steel frame, the other possibility would be that it's a bike designed for a woman or a short man. Some builders use smaller wheels in front to accommodate a shorter top tube that shorter riders require. But, the Reynolds 753 was a super-light and high-tech tubeset usually only seen on racing bicycles so I suspect you have a 1980's time trial bike.
To sell it, I would visit http://www.classicrendezvous.com/ and sign up to receive their free email newsletter. You could then post a message to the group. We're all vintage 10-speed fanatics from around the world. If you were to provide some nice photos of your bike, you'd probably get some feedback from the CR people, and you might even hear from someone who knows exactly what you have. Then you could choose whether to see it to someone on the CR list or on http://www.ebay.com/.
Have fun and I hope this helps,