(From a recent email)
The Pacific Cup is conducted under the PRHF-Downwind rating system administered by Northern California YRA. Actually, faster boats race under ORR, but you asked about your Moore 24.
YRA's site for this stuff is here: http://www.yra.org/PHRF/
For the overall Pacific Cup trophy, you need also to get your rating certified, with details here: http://www.yra.org/PHRF/ncphrf_certifiedratings.html If you do not do that, you are not eligible for the overall prize.
The downwind rating for a Moore 24 is about 630-636. See the yra site for other boats' ratings to see where you fit in context. http://www.yra.org/PHRF/docs/current_phrf_certs_DW_rating.pdf