Set New Bass Strings

[John Woodrow]

List,
What is the best way go about fitting a complete new set of bass strings.
I would like to send the complete set of old bass strings to the string
maker for duplication (20 year old Yamaha so I figure the scale will be
better than I can do).  However, I am worried about the uneven stresses of
removing all the bass strings with the rest of the piano at pitch.

Appreciate any advise.

Regards,
John Woodrow
Sydney, Australia