My thoughts on this flat look has been prime the car and block till straight , then put 2 coats of cheap ass catylized clear over it , then let gass off for a week or 2 , scuff, then spray your HOT ROD Flat look over it. At least you have some protection.
Like I mentioned its not a cheap look , IF you want protection from the elements .

PPG makes a catylized flattend clear , but its not cheap by any means , its made for the GM body cladding that they use.

SprayTech