You are setting yourself a tough target there, it would be more practical I think just to aim at a specific lowered figure using a design that gives buyers the space to drill their own pickup holes if yours do not suit..
Over all it's great, the grille area needs attention but it's in the direction that Nissan should have gone long ago. There are lots of cool little features as well as the over all shape, it's going to age well and is a great basis for mods. ❤️
Techno Toy have a pretty good reputation in my corner of the world, there is nothing wrong with the basic strut type suspension, it just needs some tweaks which JM is fully familiar with. Just remember that strut suspension is still used on some high end sports cars.
DIY tip to check the efficiency of bonnet vents on the 280ZX. Release the rear catch and drive the car at a set speed in a safe off road place to see how far the bonnet lifts up due to engine bay air pressure. The stock vents are pretty well useless, the ones I mentioned in an earlier post work well ie the bonnet does not lift up near as much.
If you are considering a double wishbone rear just make sure that it can be mounted high enough into the body so the car can be lowered without compramising the roll centres. There is not much room up there because the original suspension did not need it.
Interesting comments and I think that you have nailed the crucial weaknesses in the stock S30 body for race use. Basically the fire wall does not sufficiently connect forward to the front suspension load points. Also the attachment of the front X member which bolts to the rails, the stock four bolt setup allows flex, it's simple to add a couple of brackets forward to bolt to the rails.
Bloomin heck, go for it but I would have sorted the 2JZ's cooling issues out, some proper bonnet vents would likely do that. LS will be better in some ways though, lighter and better weight distribution if it's back close to the fire wall.