Fresh Rebuild; not starting

I'm also going to try to burp the system to see if I have an air pocket in there.
My real concern is I had some lower end chatter at start up... it almost sounded like a flywheel bolt banging on something as it rotated. Anyways, I jacked the front end up to look under it just to make sure I didnt blow a seal out and as soon as the front end came up a foot the noise went away. What do you guys think about that? Its really quiet now and idles super smooth. The timing mark holds steady with a light on it.
My buddy thinks the pump might have just delayed priming up pressure right away.

Everything is torqued to spec.
All fluids are to fill lines.

It only made noise at start up.