Jim, thank you... While hoping for additional input from Mike, please let me add some explanation and more comment...
My installer was trying to go 'by the book' (referencing 1967 #11-13/B6, rivet #5), where the sketch indicates downward orientation from the inside... There is also a RS grill page at Z22/B2, but the only variations from production I noticed there, were the nuts attaching top trim to the header panel, and the grille emblem. It is entirely possible I missed something, but those are the AIM refs of which I took note?
That said... (1) Personally I think the riveted design is REALLY DUMB. The General must have thought so too, 'cause they changed to nuts & bolts for '68 (1968 AIM Z22/A4, screw #6 & nut #8). But we're going for originality (so common sense has nothing to do with it)... (CAR is LOS 04D)
(2) In Mike's 2014 thread above, he noted examples where the rivet was installed contrary to the AIM (but more logically in my opinion). After re-reading the 2014 discussion, I located some photos of original attachment on a small number of other cars. Every one was installed going upward from the air passage (with 'pretty' side visible... 'nasty' side of the rivet facing up towards the radiator). Not sure if this is a "normative practice" or what? But when we re-do, that's what I will specify!
Hope that explains the 'method behind the madness'! Doing this again, want to make sure we get it right (or as close as possible)?
Which segues back to question on the tooling...