BB check-jams over Hero's 40bb river bet

Heads-up River | BTN vs BB | 100bb effective | Difficulty: Standard

Hero hand

A♥K♥

Board

K♣7♦2♣5♠8♥

Action so far:
River 8♥, pot 50bb
BB check-jams over Hero's 40bb river bet

Pot: 50bb   To call: 40bb

Villain range: BB river check-jam: 88, 55, 22, K8s, 76s, 64s, very few bluffs at this size

Your move: