Painless harness conundrum

[inkslingrrr]

Once more I ask the gurus on this forum for assistance…

A few questions in regards to the wiring harness I am putting in my 71 C10, sbc 350, nothing fancy…running stock gauges, however I will be wiring in an MSD box with this 🙈…now the MSD box has a purple wire and a green wire braided together which was plugged to the underside of the distributor, tach and battery position.
First question:
1. What do I do with wire #923 purple wire from fuse block
Simple question on side note… wires that are not to be utilized, can they be cut back and disregarded?

Thanks for your time