1966 HiPo 273 4Barrel Throttle Cable Bracket
That's for a '67 bracket- '66 and earlier had a throttle tab that bolted to a boss on the intake manifold.
This is how the bracket looks installed:
Here's some great pics I stole from
@cudamark showing the differences between a 2 bbl. and a 4 bbl. bracket (4 bbl. on the bottom):