318 vs. Slant value
There are a LOT of potential variables involved.
Obviously an unrestored /6 four speed car, otherwise loaded and in #2 condition in HIP paint will be worth more than a green/green, driver 318 auto car needing a fair amount of work.
All things equal (same condition, same options, comparable colors) the 318 car is worth more.
Take both the cars from example 2, and install a 340, and the difference becomes less, although most, myself included would likely still value the factory v8 car a bit higher.