I am quite confident that you can find a buyer for the roller, then sell off the other bits separately.
It is super difficult to recover one's investment in a built engine unless you are well known in the community for that engine. If you're not well known, all of the "what ifs" and "what abouts" come up. Even if confronted with receipts, doubters can still say "those are just receipts for parts. They don't prove that those parts are really in the engine." And they're right. They have to trust that the engine is as advertised.
That last pic with an installed Dallara kit is not the car you're selling, correct? The kit is still not installed?
Can you put out an asking price for the roller along with more pictures of its current status? I have a local-to-me friend interested in a solid X project.
