An updated design for development at the Providence Academy site is expected at the end of the month, officials of The Historic Trust said Friday.The Historic Trust and a Portland builder have been taking public input after announcing plans for a mixed-use development on the west side of the Academy property.Marathon Acquisition & Development of Portland is proposing a pair of five-story buildings along C Street, between Evergreen Boulevard and 12th Street.Officials from the trust and Marathon held a public open house earlier this month. With opportunities for online comments as well, about 250 people have been able to offer feedback, said Mike True, CEO and president of the trust. The feedback is being reviewed this month. True said.True and Marathon officials also did an informal presentation at Monday’s meeting of the Clark County Historic Preservation Commission. Marathon Vice President Aaron Wigod told the commission that “I want to come back to you with changes” when it’s time for an official proposal.The development proposal was part of the plan when The Historic Trust bought the seven-acre property in 2015. The mission was to keep 3.5 acres and renovate the historic Academy building at 400 E. Evergreen Blvd. Built in the 1870s, the former school and orphanage was once the largest brick building north of San Francisco.