I'd send him to Kihachi for squid that's been aged, in a sauce that contains salt & its own liver, for 15 years. While he's there, he might give the ankimo (monkfish liver) a shot.
If Diaspora still has the (I believe it's silkworm) pupa dish, that'd fit the bill.
And, I'm pretty certain Chuchay's could scare up some nice balut.
Fortune does carry a wide variety of dishes that feature off-cuts and/or blood. The sliced cow stomach dish is friggin' delicious! (as are many, many of their dishes).
The okra stews at Intercontinental and Drelyse aren't especially challenging due to the ingredients, but I swear they're the exact consistency of snot and about as appetizing. The thought of it grosses me out more than anything else I've mentioned... and I like damned near everything else at either of those restaurants.
Chicharron at a taco truck might work. It's pig skin (and associated subcutaneous fat) that's been cubed and simmered in a sauce. It's, let's say, texturally challenging.