The recall is to fit new parts. If chain isn't adjusted correctly its possible for the tensioner to break and lock up motor. The : dots are stamped into engine number, between the CB360E and the number, top and bottom of the dash mark, it looks like a division sign. If you have a 1975 it should already have the later (modified) parts
I found the print out of the original recall a couple of days ago, the actual numbers are,
CB360 & CB360G 1000001 to 1089642
CL360 1000001 to 1013033
Cb360T 2000001 to 2040600
CL360K1 2000001 to 2016592
PJ