The mod can be separated into FIXED output only -> Variable output -> Headphone output. So the fixed output can be modded with having to add the others. But you can't do the headphone of variable output mod, without doing the fixed mod.
It's supposed to be a hobbyist DIY project to occupy the time spent indoors for the winter ;). Where is the fun in getting it done by someone else?
Anyhow, I am sure we can come to an arrangement.

