Glad the drilling is being vetoed by the collective.
If going custom and in keeping with the Daccordi spangly 80s/90s frame vibe, can't you/they repurpose some overly elaborate beautiful Italian chrome clamps/guides from yesteryear to route the di-gubbins?
Although I am veering toward stick ons.
Angus was talking about getting West London Customs to do the work.
I think I will cycle over on the bike in question and chat. Whilst watching the whites of their eyes very carefully.