You did a great job on the Indy & am very interested to see your sub. Have you painted the Indy yet? I am interested to see how you did it.
On the limber holes, I use Tempera water based poster paint to blacken the holes & a Q tip to wipe the excess off. then I coat it with dullcote or a mix of dull & gloss. I did a bad job on my I 58 as I didn't get it all cleaned off before I sprayed it. Old eyes miss things sometimes.