I BELIEVE WHAT YOU HAVE IS A RAM AIR II LONG BLOCK. 2506 IS A 68 RAM AIR AND A 69 RAM AIR IV BLOCK AND SINCE YOU HAVE THE HEADS ALSO,I WOULD ASSUME YOU HAVE A COMPLETE ENGINE WITH A 70 INTAKE ON IT. I WOULD BET IT HAS A 9041 [T] CAM IN IT ALSO. NICE FIND!
