GMG, i had mentioned this before: if i were you and since laptimes are your obvious focus, i would seriously consider ZLE DSSV suspension (on sale now, see link).
This would lower your car, give you many benefits of coilovers design and Trans Am tested racing solution from one of the top shelf pro racing houses on the planet. Zero guessing here.
Sure, your DD ride quality would suffer, but then again id imagine tons of ZLEs never see a race track and folks do street those cars successfully.
Not only this, but this would position you perfectly for another future go faster mod: aero (which requires much stiffer springs and shocks to go with them).
For the price of all the parts that you are being recommended to purchase (more or less), you can do a wholesale, complete and proven suspension upgrade designed for the car. Plus position for the future. Food for thought.
https://www.gmperformancemotor.com/parts/84352121.html