shop to finish swap

6pk has pretty well summed it up.
Suggesting it could be done in a couple days sounds like something the seller would say.

No shop in their right mind would agree to it.

Im planning on something,5.9 into an older truck.
Its a daunting task.
Asking someone to pick up where someone else left off is not going to come cheap.
Good for you as a buyer
As a “basket case”