Water Closet Baseline

Hello, I am working on a large LEED CI project where the tenant is occupying the majority of an existing building. The restrooms in this building prior to construction had 3.5 gpf blow-out flush valve water closets. As part of the scope of work for this project the excising 3.5 gpf blow-out water closets are being removed and replaced with new tank type 1.4 gpf water closets to save water. Should the baseline case be the 3.5 gpf blow-out fixtures or does the baseline need to be a 1.6 gpf tank type water closet? Thank you, Brandon