Specially endorsed securities may be paid in cash or, if they are eligible Series E and EE savings bonds or savings notes, redeemed in exchange for Series HH bonds pursuant to the authority and subject, in all other respects, to the provisions of Circular No. 750, current revision (31 CFR part 321), its appendix, and any other instructions issued under its authority. Each specially endorsed bond or note paid by an agent must have the agent's payment stamp imprinted on its face and show the date and amount paid. Securities so paid should be combined with other securities paid under that Circular and presented for settlement in accordance with 31 CFR part 321.