I've driven several 67-69 Camaro's, and have driven Camaro X on the last two Power Tours. It is the nicest riding/handling combination first gen I've ever driven. Doesn't beat you to death, Marks custom Bilstein shock valving makes a world of difference in my opinion.
Let me put it another way. Usually when driving a new (to you) car it takes a while to get comfortable. This car does not, it is comfortable and forgiving right off the bat. If I had the money it'd be mine, no lie.
Good luck on the sale of it. I am sure somebody with the means will grab it up. And just in case somebody comes across this thread and does not know the car here is a little more info https://lateral-g.net/stielow/
I noticed theres no AC in the car, and the heater lines are capped off. Can someone elaborate on what accesory drive system Mark used when he built it. I believe its just power steering and an alternator/ stock damper?. I wonder if its a PITA when defrost is needed during big rain. Im gonna build mine with out air as well, but thinking defrost may be essential- Rich