project6gr fitment

I recently got 20” wheels with 285/35/20 +35 and 305/35/20 +50 was wondering what’s the lowest I can go with springs.

Was hoping someone could provide some guidance - I tried searching but couldn't find exactly what I was looking for. I am planning on some mods after the new year and wanted to see if anyone had experience with the same or similar setups. Here is what I am planning: GT350R Brake Upgrade Kit...