The first factor is threaded or threadless headset? Then the two most important measurements are the steerer tube diameter and length. Diameter is either going to be 1" or 1 1/8" most likely if it truly is a track bike. The next factor is you need a fork that has a steerer tube long enough to accomodate the head tube of your frame. As long as it is long enough you can cut it down to the right fit. Thats a whole different topic though (use search function). Other measurements like rake etc are probably secondary at this point in the game.