Humbrol is very good paint. Their enamels are among the best.
But it's a big model and it'll be tedious, and costly.
Conversion charts are just best guess, not equal=equal.
Testors is still selling very good paint in all of their lines.
I'd consider a spray can approach. With a little practice and artistic license (which is wholly appropriate here), you can get some nice "ghostly" effects with lighter gray over coats.
And stick to dark grays, not true black.
I think a clear coat is a good idea. Otherwise this thing will just eat light.
You might look at some threads where folks describe painting P-61 Black Widows.
Polly S used to sell some good acrylic grays like "Steam Power Black", "Grimy Black" and another one I can't remember. Maybe "Rubber".
Testors has a good enamel called "NATO Black".