Here’s an example meet for you to look at the times: http://www.cmsathletics.org/sports/track/2015-16/files/PPinvite16.html
The competitive 400 meter times seem to be 51 and under, and the competitive 400m IH times seem to be 56 and under. I’d say your best shot at getting recruited would be through the hurdles. Getting down to a 41 second 300 got me around 56 in the 400 hurdles.