Starter not engaging?

Okay, never had this happen before. I got a 318 out of a 5th avenue. I'm just trying to see what the compression is before I throw it in the barracuda.

I got the motor mounted to the transmission a 727 with the converter. I bolted up the starter that came with the motor, but to me it just seems like it's spinning and not engaging the converter. The start spins freely not mounted. The motor came with a 904, I can't see that being an issue though?

I've never had to shim a Mopar starter so I'm not quite sure what is happening. See video.