I think you are on the right track. While I understand the looks aspect too and lowering a bit more should be ok on spring rates of that weight don't go too low in the name of looks as it can begin to hurt performance.

If you are getting custom spring rates and decide to get your shocks revalved to those rates you should be in great shape. Since you have not yet autocrossed I won't recommend the rear heavy spring setup but I might recommend something closer together like 400/350 or 400/375. Lots of guys run stuff more like 400/450 and such but in the interest of keeping you pointed forwards make sure you are comfortable with a tail happy car first