Jeff S.-
With all due respect, I was just trying to offer other restorers an option to spray gun applied DP74LF which seems to be getting difficult to find and increasingly expensive for some reason.
Interesting that your experience with the finish of Krylon Fusion "Brick Satin" is "very flat." Your "very flat" description sounds like ruddy brown primer which is more brown and very flat. The Kryon "Brick Satin" I used has cured out now for about 3 weeks and actually has a slightly higher gloss than I would have expected from a "satin" finish. The picture I included does illustrate the cured gloss level. And, my experience with both Krylon and Rustoleum premium spray paints (non epoxy) is that it holds up very well over time as long as the surface is properly prepared (cleaned and bare metal primed). I have a wrought iron fence I spray painted with Rustoleum Brown semi-gloss (non-epoxy) 12 years ago. The section that is exposed to (Houston) sunlight (UV) has faded slightly but the section that is under cover and not exposed to direct UV looks like the day after I applied it. I haven't experienced any chalking. Given the undercarriage isn't exposed to direct UV (yes some does reflect off the pavement) - especially for restored cars that spend a lot of time inside garages, I'm not to concerned about UV exposure. Perhaps chalking that you have observed is from folks over-thinning spray gun applied paint to create the original drips on the undercarriage. If the underside of my driver coupe chalks in 5 or 10 years, I'll touch it up with some spare cans of paint I'll keep on hand. Although, I do agree a spray gun applied epoxy based paint would have better durability and resistance to chipping over time.
I am curious about what you think is off about the color. Neither color in the pictures I provided are exactly as it cured out on my car. I would agree the picture I provided of my undercarriage may appear a bit too red (I think the pic color is altered/enhanced by the camera I used). The actual color is a little less red than the undercarriage pic I provided and a little more red than the Krylon can pic background. I also understand from your excellent recent article "Restoration Support - 66 San Jose Unibody (Undercarriage)" that the color could vary in 1966 from "...reddish brown to muddy red". My newly painted undercarriage is a close match to your pictures on right at bottom of page 5 and similar to middle bottom picture on page 6 and left bottom picture on page 11 in your recent article.