78TA, thanks!
Cammer,
I'm curious about your K code car. Any pics? Interior color? Vinyl top? You know the drill...
Jeremy,
Out of all the coats I applied and sanded, I did reduce a couple of the applications a bit....more or less experimenting. Didn't hurt any and layed down a bit smoother on the surface of the bumper. I reduced one as much as 20% or so. Mainly, I just added a dash of reducer directly to the cup.
All in all though, I found my early problems with rough finish was caused because I wasn't adjusting the mixture on the gun quite heavy enough. Kinda like the airborne particles were partially drying in the air and causing a slightly 'grainy' finish on the surface.
Once I got the gun adjusted right, I probably didn't even need any reducer.