5.0. valvetrain help please..

Hello guys, I have and 1986 mustang, 5.0 swapped. (I believe the block is out of a truck if it applies to this) when car is Running it has a wicked tick that increases as rpms increase, removed intake and valve covers, all seems well besides one very loose pushrod and rocker. Very very loose. I'm lost on what to do next in fixing this. Any specs needed just ask, thanks! -Evan