Since Colt Official Police parts changed virtually not at all from the Army Special up to 1927 and the Official Police from 1927 to 1969, you don't necessarily HAVE to have actual 1943 made parts, since there's no way to tell when the parts were actually made.
Also, all medium frame Colt's used the same basic parts.
In other words many Colt parts will interchange to the point that many 2004 Colt Python parts will be indistinguishable from a 1928 Official Police.
Put them side by side, and even experts cannot tell which is which.
Bottom line, if you contact the parts suppliers demanding ONLY 1943 Colt parts, they aren't going to be able do that, since NO ONE can now know what was made when.
Since SOME parts did change slightly over the years, if you specify parts for a pre-war Colt and the parts you need are specific to earlier guns, they can help you.