PORTLAND, Maine — The contentious development process for the Portland Co. complex at 58 Fore St. could soon include an added level of oversight.

On Wednesday, the historic preservation board recommended placing most of the 10-acre parcel owned by development partnership CPB2 and principals Jim Brady, Kevin Costello and Casey Prentice in a historic preservation district.

Brady praised a 2014 report by Sutherland Conservation & Consulting and one by engineer Paul Becker used by to help make the recommendation.

“We note that both structural reports closely align in their assessments of the structural condition of the buildings,” he said in a statement. “These reports are an important guide in determining what realistically can be preserved at 58 Fore Street.”

The proposed zone incorporates the oldest buildings on the former industrial site, now used by small businesses and the Maine Narrow Gauge Railroad.

The recommendation requires a planning board public hearing before that board sends it to the City Council. Councilors must hold another public hearing before voting on the designation, which would require future site plans to be reviewed by the historic preservation board and the planning board.

CPB2 bought the Portland Co. complex of about a dozen buildings in 2013 from businessman Phineas Sprague Jr.

HPB members determined the property fits the criteria needed to create the zone because of its historic site significance, architecture and use. According to the Sutherland report, the area was first developed in 1846 by the Atlantic & St. Lawrence Railroad, which connected the city to Montreal.

The complex was used to build locomotives and other equipment for railroad use, and a foundry remained in use until 1982. The complex is a hodgepodge of 16 buildings, with two built directly into Fore Street. Construction dates range across eight decades to 1918, with an office building added in 1950.

Costello and CPB2 attorney Mary Costigan had asked for four buildings to be declared “noncontributing” and for the HPB to add language to ensure future site reviews use building height allowances that are part of the B-6 zone designation approved by the City Council on June 1.

The board agreed with Costigan and reversed itself on whether a former foundry built in 1895 and known as Building No. 4, and the former drafting and storehouse room built in 1858 and known as Building No. 14, are significant in terms of site history.

The Sutherland and Becker reports list both buildings as deteriorated and expensive to restore.

“I think it is a fascinating architectural style, but to restore it, you would have to take it apart,” board member Bruce Wood said of Building No. 4.

Board members held firm, however, on the 1918 former shop known as Building No. 1.

“I think Building No. 1 is highly significant, it speaks to peak production about what is important in the history of the site,” board member John Turk said.

One of the oldest foundry buildings, No. 16, completed in 1871, was also determined as contributing to site history.

The HPB declined to consider text about building heights, which is the primary source of contention between developers and opponents of the B-6 zoning change.

The proposed zoning change uses average grade, which would allow some development to reach 65 feet and be as high as 35 feet above Fore Street between St. Lawrence and Atlantic streets.

Opponents who formed the group Save the Soul of Portland are set to submit a citizen initiative petition on July 6 that would require the height measurement to be at flood plain.

Measured at flood plain, the building heights on redeveloped Portland Co. land would not exceed the grade level of Fore Street between St. Lawrence and Atlantic streets. In May, Brady said redevelopment plans would stop if the referendum passes in November.

Save the Soul of Portland has already gathered more than the 1,500 signatures of registered voters needed to put the question on the ballot, Rand said.

The petition would also establish a task force to inventory areas with scenic views worthy of protection and require developers to provide more details about potential site plans when seeking zoning changes.