Having some kind of grit

"Grit" is defined as:

courage and resolve; strength of character

Saying that you have "some kind of" something is another way to say that you have a "variation of" or "form of" that thing. "Some kind of grit" means that you have a form of grit. The connotation of the phrase implies that you have an exceptional or uncommon grit. Completely reworded:

You have an unusual amount of courage.

There is a significant difference between "some kind of" and "a bit" in the sense that "a bit" is a sarcastic reference to the quantity of something. "A bit crazy" means "a lot crazy"; "some kind of" carries no such connotation. Its literal meaning is very close to its practical meaning.

The word grit in this sense is defined as

grit: firmness of mind or spirit : unyielding courage in the face of hardship or danger

So saying that some has

some kind of grit

means that they are strong and usually courageous. Or willing to face danger.

So, "a bit crazy" could make sense here.