I have a big block in my 72 chevelle that I would like to order some parts for. I can't see the casting number on the back but the engine pad on the front has the serial number of C9S120537 with no suffix code. Can anyone tell me what I have. The heads are 346238, are these any good. I want to build up this motor as it is stock .030 or .040 over right now with a Weiland 7544 intake and a Holley 750 carb. I want a rumbling cam with lots of torque. I need you guys help. Thanks.