Is this a blower application? If so, broach the hub. If not, run the single. The correct key slot to use in a single application is the one that lines up to the #1 cylinder rod journal.
#1 tdc, the key should be aimed at the #1 deck. This will assure balancer marks in the correct position to use OE timing mark location.

"use it 'till it breaks, replace as needed"