Thank you Sporgon, but for the photo I need to take stitch is not possible for the type of work the client requires.
And I think I need medium format and not large format. Am I right about this?
Once you have completed the stitch you are left with a single image file like any other, just much larger, effectively shot on a larger format. It can then be edited in the same fashion as any other file; there's no difference.
If you really wanted digital large format we could help you out with that. We are the UK agents for one of the best known large format cameras. But there's no way you need that for what you've been asked to do, so that leaves you with medium format, but again, personally I don't think you need it.