I may have screwed up ....more than once

You may need to rotate the crank/cam. The LA heads don't get oil all the time, depends on the position of the holes in the cam. Can't comment on running the pump backwards but I'd be surprised if it was hurt. May just need to prime it.

Pull the plug on the pressure sender like it was initially and see if you are getting anything. Always good to have a mechanical gauge connected at this stage too.