I'd have given him an Oscar for this performance, especially for the two scenes you mention (the confrontation with his parents, and the scene when he confesses about Wilson). As for the film itself, I think it's a magnificent piece of work. Probably Oliver Stone's best film (though I'm a big fan of everything he made between Salvador and JFK). I don't really share your reservations about this film, to be honest, as Oliver Stone (or Oliver Grindtstone, as my father called him) may be a blunt, melodramatic instrument, but he's a hugely effective one. It's just a shame most of his later work is so unmemorable in comparison.

Great retrospective by the way. I recently wrote about this too (see link below if you're interested). :)

Born on the Fourth of July: 35 Years On | Fanfare