I ran into similar questions when building my locost (84 celica GTS donor). I swapped the uprights side-to-side to make them front-steer to accommodate the modified spitfire steering gear. This give the car negative ackerman (toe in during steer).
I dont want to make comment on the parts you...
Keeping the scrub radius as close to zero is a must have for traction related compliance(s). Otherwise your KPI should be defined by your desired suspension geometry (kinematics).
Be sure to consider traction (accel and braking) when you define your rear camber gain (dont have too much!). You...