I would have to say that to me a complete chassis would be exactly that "complete" in other words ready to receive all the other components without use of a welder.
I dont want to teach granma to suck eggs, but would suggest you build a complete car first then build chassis to the same spec to sell as then you can be confident that nothing has been forgotten and all the bits fit.
Thats what i would do if i were to offer a chassis for sale as "complete"
Ray