I have done many albums along these lines and have never failed by stitching them down with 2 strands of 8lb test monofilament laid out the same way as photo corners. Lay out the album in position, mark the corners with low tack tape or post-its, mark approx. 1/2" either direction of the corner in all four corners, remove cover leaving tape, using the marks complete a triangle that will take about 3/8" behind the album cover, at the tip of the triangle pre-position a stitch with a loop big enough to work the album into in all four corners, replace the album and weight it down so it will not move at all (I like about 6 thick phone books), pull the loops over the corners of the album and tie them off with reasonable tension working on diagonals. When you remove the weight, the album should be in place securely. Tip: if the actual record is in the cover be sure the open end of the inner slip is inside the cover, if there is no record put a piece of mat in the cover as a stiffener. If the monofilament is too shiny for the customer slip a business card behind it a gently buff with 0000 steel wool.