With my 350 finally going back together, I came across a small bracket that I can't identify (see photos). The engine in question was/is a '71 350, 2 bbl carb, auto trans, and I believe came from an A/C car. Based on the witness mark around the bolt hole in the bracket, I'm thinking it bolted to the intake manifold via one of the intake-to-head mounting bolts.
Yep, got one of those. With the Stage 1 intake and the Holley carb, I didn't bother putting it back on. Now, with a QJet, I may see if I can get it back on.