trackday vs raceday = a very slippery slope
This looks like a very nice build and agree that 'track day (Grp 1?)' and 'race day (Grp 2-5'?) builds are two different animals.
One must ask how will the car be 'enjoyed' most? How often to you want to drive it?
That being said, I consider a 'tweener' as a street legal, gentleman's weekend racer (Grp 1) that can be driven to the track, stopping at the market for 'supplies', enjoyed/flogged on the track harassing others with a sh*t eating grin, then driven to the pub afterwards to tell tall tales of the day's track battles....and maybe you'll drive it to work the next morning all numbered up from the weekend for more breakroom BS with the your gearhead coworkers...the build will likely bit a bit harsh for everyday use, but is doable, but never quite sharp enough to be in the front on track, but will show taillights to other 'road cars'. In short, you can use anytime
A race car (Grp2-5) will only see the track/paddock tarmac, garage/shop and trailers.....but will be tremendously fast, satisfying lovely beast that consumes many things...
My brother built a 'unique' E9 race car (no interior) with his own custom livery, I built a E9 'tweener' homage with a 'functional' interior and custom 4pt cage. Both are very satisfying to the owners and able to be on track together (ie: at certain event types), but how they get there, budgets and laptimes are very different....