Ah, the lovely gray primer.  I used Sherwin Williams PrimeShield PSE-4600 epoxy primer for the undercoat.  The epoxy primer will seal any bare fiberglass strands so the topcoats don't sink into them later.  The down side is that the primer itself is not a high build surfacer, and doesn't hide or fill any imperfections that aren't miniscule.

My buddy Neil is The Man (tm).  He shot the car for me, both the primer and the door jambs.  Not a single run in any of it.  We shot everything in my garage using his compressor and a Finishline HVLP gun.  It turned great.

I set a deadline, and worked like crazy to get the body straight and smooth ready for the first primer coat.  I wanted to avoid having to spray it twice.  Wishful thinking!  After that first coat of primer went on, every single flaw that was hidden by the multi-colored primer/glaze/bare glass was now visible.  I was and dejected and disappointed.  I knew I'd have to spend dozens of hours sanding, filling, and correcting my mistakes.  Plus, every single bonding strip between the panels was visible too.  I feared the worst on that, having to sand down and fill each and every seam.

The happy ending is that once I started sanding the primer, all the seams smoothed out and  I didn't need to fill the seams.  I sanded and smoothed the high spots, filled the lows, and Neil shot another coat of primer.  Then I wetsanded the entire car with 600 grit paper before we shot the jambs and trim parts with the base/clear.  For block sanding I used an 11" sanding board, a 4" sanding block, or a soft sanding sponge depending on the size and shape of the panel I was working at the time.  I blocked all of it using a "cross-hatch" pattern to knock down the high spots and smooth the orange peel in the surface.

Here's the primed car after the second coat was sanded.

Then we masked the car off to shoot the jambs, the insides of the doors, and the engine compartment surround.  That's when I really started to get excited about how the car was going to look.  The color looked awesome in the can, and really nice on the car.

Onward to the  Finished Product