Go to bikebandit.com Pick the year and size, then OEM.
Now go through the schematics looking for the part you want.
The 1974 450K7 shows the chain and the softlink.
$101 for the combo.
Caveat: I don't know 100% that will fit, but that was one of the ones I remember being listed as working. Maybe someone else can confirm.
You can always get the part from your local Honda dealer too.