Need help keeping up with C6 Z06 & Porsche GT3 on Road Course

I just read up on a post on another forum with some computer program images regarding bump steer affects, etc. Looks like lowered factory spindles are okay in that category, and the 2" drop spindles are slightly worse. Not to mention, they determined the roll center height was higher with the drop spindles.

I'll aim for the measurements given (5.25" k member) by you, and stick to what works.

I've been researching everything for the last couple days, looks like my shopping list has grown! No surprise there.

I'm looking for an old 275 35 18 scrub to mount on this wheel for checking fitment- know anyone who's got one that is heat cycled out? The tires I plan to run are 275 35 18's on all four corners, used continental racing series tires. They seem to be in abundance and cost $50-100/tire after a few heat cycles. I just need to make sure I can make them fit.
I have 18x9s with that tire and no rub anywhere. If anything I bet you may need a 3/8" spacer. Mine is tight full lock left at the bellcrank bracket on the frame rail which could be trimmed if needed but in a real world scenario im almost never full lock left and if so the tire sidewall would pull away from it anyway.