Hello pinball,
Welcome to the DigiKey Electronics.
The BA has a repeat cycle of 10.5", with 2" flat, so there is 8.5" where it is twisted.
The cut pattern will be random, as it depends on where the last cut had to be made.
So it would be smart to add 1 foot to the length you need, to insure you have the correct number of flat sections.
The 1700/40 will have 18" of twisted pairs, and 2" of flat section, with a repeat length of 20".