I think that I got the attribution mostly correct, but I don't have any Bosporus references yet; but I did just order MacDonald: AN INTRODUCTION TO THE HISTORY AND COINAGE OF THE KINGDOM OF BOSPORUS, which should be interesting.
Rheskuporis V
King of the Bosporus
AD 323/4
AE Stater
16x17mm 4.6gm
Obverse- Draped bust of Rheskuporis V facing right with a wreath of pellets before.
Reverse- Laureate and draped bust of Constantine facing right, K/X in fields.
MacDonald 679
KX= 620 BE= A.D. 323/4
