As Grandpa said, the regulations vary from state to state, so knowing what state you’re dealing with is the first question. I had to go through a specialist when titling Lockjaw, my first rat rod. It’s built on a Nissan pickup frame and made from items off of a dozen other vehicles.
Another important question is, what year vehicle is your chassis from? It matters in some states and some vehicles didn’t have VINs on the chassis or body. Model T and A Fords were titled by a number on the engine. That causes problems in some states where the original engine is not available.
What body are you planning to use? You may be able to title the vehicle using the VIN from the body.
Finally. You may be able to obtain assistance from your state DMV. Ask questions, a lot of questions! I found folks that walked me through the process at the DMV by carefully explaining what I was doing and seeking solutions. They were helpful and I actually made a couple of new friends!