This article should help!
http://www.tikimanpages.com/poly/the-resort/planning/item/60-which-longhouse
FWIW, on our one visit to the Poly we stayed in Moorea (a DVC-only building) -- which is one of the longhouses that is furthest from the pool and Grand Ceremonial House. Even though it looks far away on a map, the walk to the pool and/or GCH was no more than 5 or 6 minutes. The longhouses with standard and garden views are all much closer than that to the pool and GCH, so even if the Poly is not able to satisfy your particular longhouse request, you won't be too far away from the heart of the resort.