Very pretty under your car George. Blue works
.....Ash Gold does not
What you wrote falls exactly in line what I found under my Z. Wondered why the gray ? ( and front 20% pretty accurate)
under my tank (trunk) was barely any coverage what so ever ,had the car sat out over the years , it would have long since rotted away. presented almost as bare metal with very lite surface rust.
Looks like you pretty much nailed what it might have looked like before the undercoating.