Hi Edd, Welcome to the forum,
You will need a 25.5" Scale length neck if it is a genuine fender body,
Wood types are preference, although if you want to keep it Authentic then either an all maple neck, or maple neck with rosewood fretboard.
The headstock is personal preference, you can either stick with a traditional telecaster headstock or change it a bit, a few companies are selling paddle headstocks now so you can make your own.
You will have to be wary of the heel shape of the neck to make sure it fits into your neck pocket, fender neck pockets are usually rounded on the edges, and some copies are slightly different, although if your careful you can usually shape them to fit.
You will probably also need to shave some off the bottom of the neck heel as many companies leave them larger to fit a range of instruments.
With regards to frets, 21 is the norm for tele's. You can also look at wether you want your truss rod accessed from the head or the heel. My personal preference is the head.
Check out some here:
http://www.axesrus.com/axenecks.htm#TeleNecksThere should be something to suit you on there.
If you need any more help feel free to ask
Thanks,
Tom.