If your car is completely stock, the Ford 60 Amp alternator should be fine for your application. You can probably get one at your local autoparts store.
If you've added additional load on your system with hi-flo fans, hifi stereos with power amps, super-bright headlights, et cetera, you may want to consider getting a 100A or greater output alternator. It also allows a faster recharge for your battery, especially during night drives when there your alternator is working the hardest.
Be aware though that if you do consider a hi-amp alternator, you may need to upgrade the charge wire accordingly as your stock 'Lucas' wire may not be able to handle the increased load. View the manufacturer website for assistance in choosing the correct gage wire for your application. My 100A alternator upgrade did not require upgrading the charge wire.
Good luck