They say a picture is worth a thousand words:
If viewed from the "hood" side where the connector is flat, with the wires going down, and the mating side of the connector up, then the positive side is on the right.
Other amateur radio sources that corroborate this orientation:
Beware: this is a recommendation, not a standard. Hopefully within amateur radio people observe the ARRL recommendation, but Powerpole connectors are made of individual pieces which can be stacked in any orientation. If you do an image search you can find examples where people have assembled them the other way. There's significant potential for an expensive mistake here.