Suggestions on getting 70+ MP from 5D II

Hi, I am assigned a job to get some photos of 70+ MP. And I am going to use 5D II to do the job because of the limited budget.

So right now I am thinking of two ways to do it, and is stitching 9 photos to get about 80+ MP, another is to use photoacute to synthesize a couple of photos of the same thing and get 4 times the resolution. Which one do you think would be better?
And for stitching, I dont have a panoramic head. Is it necessary to get one?
And any other suggestions on equipment/technique/workflow?
Thanks in advance.
PS the photos are outdoor photos of the buildings of the organization.