A 3.3-acre property at 139-149 Washington St. in Brighton would be redeveloped into a 250-unit residential complex by AvalonBay Communities under a recently filed proposal.

The 363,000-square-foot development would include demolition of the former St. Gabriel Parish School and convent/rectory buildings and construction of two 5- to 6-story buildings containing condominiums and apartments, according to a submission filed last week with the Boston Planning & Development Agency.

Designed by CBT Architects, the AvalonBay proposal calls for a 220-unit apartment building and a 30-unit condo building, along with 250 parking spaces. After a series of community meetings that began in March, developers shrank the unit count by 13 percent, reduced the building height along Washington Street and added the condo component.

AvalonBay has a purchase-and-sale agreement on the property, which is owned by the Archdiocese of Boston.

The two buildings on the site are currently occupied by the St. John’s Seminary Theological Institute and ABCD Allston-Brighton Head Start.

The property is across the street from the former St. Gabriel’s church and monastery property, where Boston-based Cabot, Cabot & Forbes has proposed 679 housing units, including three new buildings and restoration of the monastery building.