I really like your paint job! Looks great on the Camaro!
The Revell 69 Camaro grilles are great for opening them up. I did that on my Baldwin Motion grille, and the one I used to replace a 60 Impala grille. I used the Dremel with a sanding drum to get most of the plastic down, going slowly, and checking progress. Then switched to a course flat file, then a finer file, before finishing with some 600 grit paper. Didn't have much clean up after that. You have to be careful, as there isn't much support left, and it could be broken if you aren't careful.
So...with regard to your request for suggestions. If you are going to use black and tangello underhood, I'd go with the tangello on the engine, and black on the surrounding areas (firewall, fenders, rad support). That will allow the engine to stand out. You could do the chassis floor in tangello to match the lower body, then the front sub frame could be black, or tangello. Have fun deciding!!