A wall assembly is provided for a gas turbine engine. This wall assembly includes a support shell with a contoured region; and a multiple of liner panels mounted to the support shell. At least one of the multiple of liner panels includes an end rail. The contoured region is deformable to selectively contact at least a portion of the end rail. A method of assembling a wall assembly within a gas turbine engine is also provided. This method includes locating a stud that extends from a cold side of a liner panel through a support shell; and attaching a fastener onto the stud to at least partially close a gap defined between the panel and shell.