Just wondering does anyone have any experience photographing panorama's for virtual tours?

I've been asked to shoot a chain of BBQ stores in Sydney, we've done a dry run (which the owner of the business loved)... but I've learnt that my pano's aren't the right ratio. I need 2:1 for the software to create the pano. Is there a simple calculation I can do of how many shots high and wide I need to complete this? Or is it simply a case of trial and error? Especially factoring in lens distortion and overlapping areas. (One thing I learnt on that shoot was all about lens distortion....grrrr)

The Pano's I took last time worked - but needed to be cropped to create the tour, so some of the warehouse was missing.... I really want to be able to give them a 360 deg view.

I can supply an example later tonight when I plug in the external drive