I have a pair of NOS hood emblems (GM # 25519633), and they come with adhesive tape already applied & trimmed; just peel off the wax-paper-like protector & stick them on.
Applying tape to an old, removed emblem looks impractical, even using narrow 0.25" 3M tape (# 06385 or 06386).
One possibility is to use 3M # 08061 ([FONT=Arial,Bold]Plastic and Emblem Adhesive), and squeeze out a narrow bead from the tube, onto the emblem backside. Data sheet PDF is attached. [/FONT]
[FONT=Arial,Bold]But I've never used this stuff before, so I'd be very cautious applying it to visible paint ... maybe try a concealed location first.
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