727 experts? Need help

Was the park rod on the valve body when it went back in?
Did you have to rotate the driveline or output shaft to get the rod in place?

When the linkage rotates the button on the end of this rod gets pulled into the park pawl and the pawl gets pushed over into the teeth on the park gear.

As far as no fluid coming out of the line it almost HAS to be the pump, (where the converter snout goes), the filter or not enough fluid in it yet.

Any of this sound probable?

Any of the park lock parts missing in the tail housing will cause park not to lock also.
Lucky that all those parts except the attaching point for the rod to valve body are in the tail housing, so if the rod is on the valve body you only have to pull the tail housing to see what's missing.