I'm a former 'stang owner. I had one (vintage '68 or '69, the red one with the racing stripe) for about 10 years, and just sold it recently.
I think you'll definitely be better off with a Warmoth Mustang than a Fender, and here are a few reasons why: You want to use a different tremelo than the original. It gives none of the advantages, and all the disadvantages of having a trem bridge. The bridge rocks back and forth independently of the tailpiece, so any trem usage results in the guitar going out of tune. To adjust the height of the bridge, you have to take off all the strings and remove it from the guitar. You then adjust the posts by hand, using your best guess as to where you need to be, then reinstall it, and restring. If you guessed wrong, the strings have to come back off, and the process is repeated. The short scale is a horrible idea. It felt awkward, and not as easy to adjust to as going from 25.5 to 24.75. Light strings will be really floppy. However, heavier guage strings (11 or higher) will cause the tailpiece to pull forward enough that there's almost no dive in the trem bar. The only way to correct this is by completely removing the trem unit from the instrument, as there's no strat-like trem access on the back. The pickup switching system is ok for home usage, but unusable in performance. Each pickup has it's own on/off/out of phase switch, and none of the settings are good for rhythm & lead. Most of them sound very similar, as well. Mine had replacement tuners, so I'm gonna assume they didn't work very well, either.
It was the first guitar I ever owned, and I have yet to regret selling it.
