Timing Question - Timing Cover or Balancer switch

A friend was very nice and gave me a 318 engine that he had. The time chain cover and balance and lower pulley were on the engine. I added other pieces and parts and struck the engine in my 68 Dart. I made sure the number one piston was at TDC, I made sure the distributor gear was lined up at the bolt hole near the number one cylinder. I then installed the distributor. I installed the intake manifold and the carburetor and fired her up.

She runs good, I set the timing by ear. Then I got the timing lite out, plugged the vaccume line, plugged the hole in the carb, set the idle, then I put the timing lite on it, and the timing is 37.5 degrees off?????

The timing lite showed that the timing was off 37.5 degrees?????

I did tell you that the engine runs good. Could the person who put the engine together have used the wrong timing chain cover, or the worng balancer and cause me to be that far off??

If I have the wrong cover or balancer what should the timing be off by???