The contract may provide that the association may sell or resell the fishery products delivered by its members, with or without taking title thereto; and pay over to its members the resale price, after deducting all necessary selling, overhead and other costs and expenses, including interest on preferred stock, not exceeding 8% per annum, and reserves for retiring the stock, if any; and other proper reserves; and interest not exceeding 8% per annum upon common stock.