I'd just put plumb it to the cowl and have it spray on a angle kinda towards the windshield. Ive always wanted to see a ricer have it purge from everywhere on the car, so its like a smoke show or something complete fog!
If you had an SN95, I'd say have it come out of the "nostrils" of the hood. Up in the cowl grille near the washer squirter seems like a common, easy, and tasteful place to route it. If you have a ram-air style hood, you could shoot it out through the front hole(s).
I've seen someone before with an SN95 have the purge nozzle coming out of the butt of the chrome horse in the grille.
The coolest ones I've ever seen wwas someone who deleted the dot (.) from the 5.0 fender emblems and plumbed it to both so that the nos puged from both fenders!
The other one that I like and will be using is an atenna delete plate that has a purge nozzle in it. Can't remeber who sells em but they are available.
That antenna plate idea sounds cool. Couldn't you just unscrew the antenna and purge it through the threaded hole just the same as you could with a delete plate?
i ran some brake line from my purge noid. along the hood seal, through a hole that was already in the firewall, under the cowl panl. it sits flush with the venting, close to the washer nozzel. and shoops up at an angle similar to the windshield. shoots a nice big plume...