To me it comes down to the condition of that red interior.
You can paint any Z white and put a red interior in any car, but the red stuff is hard to come by in good condition. If you're going to have to replace most/all of it anyway, it might be better to find a more solid starting point. If it's all there and all in good shape, then it could very well be worth your money and time to pick it up.
Like Plata said, projects like these are all about feeling good. If you think the car is a good one, then go for it! You've done enough buying and selling of s30s to know what's worth your time and what isn't