Hey dude, having the same problem with mine- either no one knows what it is, or when they talk, show they don't know what they're talking about- I've lost count of the number of times somone looked at my car and said it was a variant of the levin/trueno- Grrr!
When I first saw the car in the Automobile Year annual, they basically said that it was made to compete against the Nissan Silvia in terms of appearance, since it was outselling both the Honda Prelude and the Celica combined... they also said that the running gear is the same, as is the switch gear- too much to list in terms of similarities, so the only real difference is the body work- oh, and the fact that there's no GT-4 version
Interesting to note though that the US celica has a boot, not a hatch- so designing the Curren wouldn't have been much trouble for them... besides, the Curren is better looking anyway!
You should not have any problems getting springs- as Perky says, codes are identical, so going for Celica springs will see you right. Have you asked Mr Revhead?