You are making some good progress! Going back about 7 pages and reviewing, I like the dual orange stripes with the blue v. the single so I say go for your rendering. Definitely adds dimension to the look of the car.
As for signals, find a 3-way toggle for the dash, neutral being off, with up and down for on, sorta like a lo-hi switch. Then just mount it sideways on the dash and hold it on for left and right. I put a button on the dash of the 914 for the horn. As little as you will use it on the street, simple buttons are good enough.
That Butler seat can be reworked, or simply heated a bit and bent at those rib supports. Those containment seats are great - I wanted one in the 914 but it just simply didn't fit in that small of a car - I couldn't get in and out with it. Depending on how the Nova goes I have some padded "ears" for my Ultrashields that I can weld on. In your Camaro you should have no problem getting in and out with a removable wheel of course and having that additional head support should be great.
That is some crazy exhaust! I agree with balancing after the mufflers to try to quiet it down a little more - you should be able to fit an X-pipe in that mix as it comes across behind your seat. I can't say I have done this and personally proven to myself the validity or know the difference, but have
heard that it helps. Maybe it is only good for 1 or 2 dB but sometimes that is all you need.
As for that Merc9 car, while it is cool to look at and I do think it is pretty interesting, don't do what he did. I ran 125-130 mph thru the sweeper and 165mph down the straight in the 914 with no aero, no cage or tubing, horrible 914 suspension, on the first track day after I first did the V8 conversion. Of course, I immediately disassembled the car and started a full chassis once I realized how crazy it was going to be

Nonetheless, that car should be closer to 150mph in the sweeper with all of that work and aero, so again, don't do that

Well, except for the sequential transmission - those are nice