Go to http://www.floydrose.com
and they have the chart sizes for the lock nuts and tremolos there although you really don't need to to replace it right away. For the nut you're going to have to measure it to get the overall length (that will be the "R" number) followed by the actual E to E string spacing. It's best to use one of those little 6" machinists ruler's that measures in 32nds of an inch and mm's. Mine actually has mm to standard conversions on the back and I'm pretty sure it's made by General tools. It's good quality and cheap too, around $10 maybe.
If the trem says "Licensed by" or is a "Charvel/Jackson" branded it's not a true Floyd and you really have to check everything to make sure it will fit, unfortunately you fall into this category. dropping one in depends on the measurements. The posts may need to be doweled and re-drilled or the tremolo cavities routed more. Depending on how much money you paid for the guitar in the first place look at about $300 for the Chrome model and they go up from there, plus another $100 for a proper setup from a repair shop, and another 50 to 75 if there's woodwork to be done.. I wouldn't advise going this route unless you really want to spend another $400 or more on a lesser priced guitar that you've already put pickup's in. I've been fixing Guitar's for about 25 yrs now so I want to give you an honest opinion and that would be to forgo the new trem and either trade the guitar for one that has a true Floyd on it or just use what you have.