Any employee of Palmer College, or any other State employee, on July 2, 1974, who was as of July 1, 1973, an employee of Palmer College may avail himself of prior service credits under the South Carolina Retirement System in accordance with the provisions of § 9-1-860. Provided, however, that such prior service credits shall not be extended if to do so would adversely affect the tax-exempt status of the South Carolina Retirement System plan.