Found plenty of out-of-copyright Malaya (what was a part of the present Malaysia) maps, archived by the National Library of Australia.
The NLA freely mentioned these maps are out of copyright. Also, they provide download links in both JPG and TIFF formats.
Would love to use this (to improve #OpenStreetMap for sure), but probably would hear any precautions before straight using it for mapping.
For obvious reasons, some places e.g. hamlets are now has disappeared.