Is this wrong? No. You'll see above that PCI_raid has them on his. But are poly locks "correct" for a 67 Pontiac in terms of originality? Also No.

Take the following with grain of salt as I'm no Pontiac pro. Generically speaking:

Poly-locks are fairly commonly added as part of a performance upgrade, on a Pontiac it seems they usually are put in in conjunction with changing out the factory rocker studs, and they are pretty much mandatory with an upgrade to full roller rockers. You don't often see them on factory stamped rocker arms, but they are absolutely necessary if you want adjustable valve lash, which is often needed if you have a very aggressive camshaft profile.