I used KBS Diamond finish on the under side of the car. I like the finish and the way it applied. My opinion it is tough. DON'T MAKE A MISTAKE WITH IT! Trust me I know. When you open the can plan to use it in 6 months. put marbles in in it as use it. If you don't need much get a spray can I think it covers 30 sq' per coat,per can////On the motor I used Duplicolor Engine Enamel, Chrysler Hemi Orange, 12 oz. Aerosol Part # DE1652 and clear VHT Paint VHT Flameproof High Heat Coating Paint - Clear Part # SP115. I like the way it's holding up so far. Hours of running and no blistering or peeling. Also used the VHT clear on the trans on a rainy day and it milked up. Cleared up about a week later.
POR seems to work very well. It’s really about the prep.
I have used their metal etch and prime. Make sure you’re well ventilated and a good respirator as this stuff is dangerous (as all is) if inhaled. After the cleaning, etch and prime, I ended up using the factory mopar spray paint. Just wasn’t comfortable enough with the homemade tarp and fan. Comes out really nice.
Good luck
For Hemi application I used the Hemi Orange PPG Duracryl formulation -HEPPL, from Frank Badalson/Roger Gibson. I you are looking for the real deal 69-71 Hemi Orange it is the OE recognized finish. They also have other Hemi year and RB and 340 color formulations for performance years.