I have created a panorama using about 6 images all taken using a 17mm lense
(with a Canon 40D).

At a later date I went and took some more shots (from the same
position/location) but with focal lengths of 35mm and 50mm.
I now want to add these extra images into the original panorama without them
looking disproportionate or appearing to have better or worse resolution.

What is the math I should be applying to ensure I get the extra images at
the same proportions as the panorama and also preferably at the same
printable resolution?

My idea is that the 50mm images will need to be reduced in size to 17/50 (ie
0.34) to fit correctly into the panorama. The 35mm images would be reduced
to 17/35 (ie about half) to fit into the panorama etc etc.

Not too sure what to do to ensure a consistency in printable resolution by
mixing images (of differing focal lengths) in this way.

thanks

Benny