the holes are there remove old window and rubber, rivet hinges etc into B pilar and the opening hinges with original screws your done, the b pilars already have the cut out and the c pilars are easy to trim and i beleve have the bit marked to cut

or get s2 opening rears, ok expensive (i know ive had loads) and matching colour class, much better

i use rivets cos its eacy, ford used clinch nuts and screw, its hassle and rivets are easy to sort, dont force a screw or bolt in as it'll pop out and bust your glass