1969 COPO 427 ?

[MAC101010]

OK ITS BEEN A WHILE BUT I WAS ABLE TO COME UP WITH SOME MORE CASTING NUMBERS
(1) BLOCK # 3963512 ,DATE C-31-70
(2) CYL CAST # R/S 3964291 D-18/70
(3) CYL CAST # L/S 3964291 E-7 /70
I AM LED TO BELEVE IT IS A 427CU.IN. 425 HP OR A 454 LS-6 460HP WITH A EXTERNIL COUNTER WEIGHT ON THE CRANK. I HAD A METAL URILGIST COME OUT AND HE SAID THE BLOCK HAS BEEN DECK WHERE NO VIN NUMBERS COULD BE RETRIVED. I ALSO WAS TOLD IT COULD BE A 1970 NOVA COPO 427 MOTOR ? I will try to check the stroke bye using a flex tube and measure the stroke to see if it is a 427 or 454. Any sugestions as to try to find out what kind of motor I have would be helpful.I check the crank and it has a externial counter weight on it but could not find a cast number ? IF ANY BODY HAS A SUGESTION WOULD BE GREATFULY HELPFUL. IT HAS A SOLID LIFTER CAME.