Size for Full-Bleed Image for 8x8 Seamless Layflat Photo Album?

Two-page seamless layflat spread source image would be 8.25x16.25, according to spec and including all-edge bleed. But that size image winds up being .25" short on each side when embedded in two 8.25x8.25 facing pages, displayed as "facing pages." Should the original image size be 8.25x16.5? If not, what's the spec to achieve full-spread bleed on a photo album this size?