I know of New Era Performance in the Augora Hills area. Their webste focuses on tuning (which I know they're good at) so I don't know for certain what kind of motor and suspension work they do. Also, from their YouTube videos, it seems they focus more on Drag racing but it's worth a shot emailing Alex and asking your questions.
alex@neweraperformance.com
There's also n7 Engineering Solutions in the Wilmington area. The owner Matt (n7maro on Instagram) owns a ZL1 and he's responsive on Instagram and Facebook.