A couple of corrections:
1. Motors from 1978 forward were not numbered with the 447 prefix although (in North America at least) they were 447 series motors.
2. Wrist pins from 70-73 were 22 mm. OD. From 1974 forward 20 mm. pins were used.
3. If you're using OE or OE replacement pistons, any clips from 74 forward will work. If you're using aftermarket performance pistons, be aware that clips must fit the grooves in the pistons. Venolia pistons, for example, are grooved for thicker wire than OE clips use, and installing OE clips in them will cause trouble sooner rather than later.