This is a ridiculous idea. I like it alot, but can't foresee it being feasible.
If your goal is to hide the vent lines, or place them in a better spot for the "wow" factor, or just to be different, don't move the vent lines to cover up the coilpacks. That's just not a good idea at all. Those things need as much air as possible to dissipate heat. A vent line made of whatever material, sucking through hot vaporized motor oil doesn't help the situation.
It is definitely possible to get vent lines inside the coilpack valley, but I would go with an aluminum A/N weld-on fitting.
Earl's 997112 Aluminum -12AN Male Weld Fitting - Haloway Express Merchandise Center
But, just as Codyace pointed out, the size/manufacturer of the adapter will dictate the size of the weld-on A/N fitting. So, I'm thinking small, possibly -3 or -4.
At those sizes, you would probably benefit from 2 (or 3) vent holes feeding into one hose. I have no idea how this would affect your motor, so in my mind, this could work, but I probably just sent some old Japanese Nissan engineer spinning in his grave.
Look at dressing up the motor by welding A/N fittings to the current vent holes and get stainless steel lines.