[font=trebuchet ms]If I interpret your first post correctly, you have the neck, a (badly) re-finished body, and a few bits of hardware. I also get the sense that you aren't interested in doing a 'cork-sniffer' absolutely correct restoration.

That opens the door for doing anything that gives you a playable instrument. Since you intend to refinish the body anyway, You just might find that filling in the tremolo cavity is a good way to go. If you want to have a functional tremolo, I think you would get a better bang for the buck by buying something more modern. A used guitar will possibly work out to be less hassle. If you turn the Mustang into a hardtail, you can also make it string-through-body for better tone. And there's a world of aftermarket pickups available, to give you any kind of sound that tickles your fancy.

So take a look here Allparts guitar parts,
and here Guitar Parts Resource,
and here bartolini pickups and parts,
and here DiMarzio pickups,
and here EMG pickups,
and here Fender,
and here Guitarnuts sheilding techniques,
and here Guitar Trader parts catalog,
and here Higly Strung guitar parts,
and here Lace pickups,
and here Musical Instrument Makers Forum,
and here Seymour Duncan pickups,
and here StewMac guitar parts and luthier tools and supplies,
and here USA Custom Guitars guitars and parts,
and here Warmoth guitars and parts
for some ideas.

The only limits are your imagination and your budget.

Have fun![/font] :D