Go to where you get your license plates & tell them what you have done & get the forms you have to fill out. In Florida you have to save receipts on all major components. You will then probably have to go thru a safety inspection. My county in Fl requires no emission inspection, your State/county might be different
The important thing is to find out what you need before you start.
There is a web site that tells what you need for each state. Do a google search.