Jagged edges on objects as camera moves about

Unfortunately I've been directed to turn off morion blur as I'm working on a 12fps scrollable animation.
usually the TAA works fine but for some reason the camera's not liking the geo the it pans up little up, down, and around. So I'm blending an FXAA pass with a TAA pass in post - FXAA is treating the edges better but falls down in the areas. I wonder is there a way around this. Unfortunately I have no control over the size of the mesh and export settings to me (36 million triangles), but, that's not the issue, cos Unity handles this gargantuan, over-cooked mesh with ease! Can't believe how light it treats it! Amazing! Maybe my units be an issue? Its a straight import of a Maya file setup to correct meterage, but comes into Unity way massive!

anyways, any tips be appreciated!