An Intriguing Small Bronze Coin. Kephaloidion?

This small (15 mm diameter) coin turned to be not clearly assignable... to me of course.

I suppose it has been minted in Kephaloidion (Sicily) around or after 340 bc, over an original coin of Syracuse (?).
R) pegasus running right with a sort of countermark at the extreme right
O) Young Herakles facing left.

On the reverse and above the pegasus there seems to be a chariot running to the right, that I suppose is a residue of the original coin. On the obverse, traces a letters from the orginal coins appear under Herakles head .. maybe an O and an N?

However, the most intriguing element is the symbol at the extreme right of the reverse. I guess it is a countermark, but I'm really not sure. There seems to include a lion head facing right with something before it and something above.

the coin and the above details are shown in the appende images

Could some expert confirm my suspicions or give some alternative suggestions?



REVERSE



REVERSE 2



OBVERSE



REVERSE DETAIL OF COUNTERMARK



REVERSE DETAIL OF COUNTERMARK 2



OBVERSE DETAIL