I'd say go with a wait and see attitude lol. You'll have a highly detailed model for your own use that way (whether it's ff7 friendly or not) and the experience of making it. If your finished model is really too dense you can always use retopology. I'd say go for as many polygons as you can possibly fit into FF7 and maintain your detail, since you can only use a diffuse texture. You can use photoshop to add more effects to the texture so it doesn't look as flat, but it wont look the same as a more detailed model. Usually this isn't what you want to do for a game, but FF7 works a bit differently than other games and since you cant use normal, alpha, specular, or any next gen texture mapping it'll work out ok. I checked my largest model and it's actually about 60k. I had issues with kimera crashing (there are work arounds for that though) but it works fine in the game.