CAn I down grade my frod F100 to a 4.9 L from a 6.6 L? on 1990 Ford F-150

I have a Ford F100 with a 6.6 L

Asked by for the 1990 Ford F-150
sure can if you have a boat load of money and time
Thank you for your reply. Are there any steps or proper notifications that I need to do through DMV or anyone? Will this affect smog?
yes it will be a visit to the BAR or referee station to get whats called a new bar label. this maye your worst nightmare of your life.