I have a copy of the ad for these rifles from the 1965~66 time frame. The rifles were imported by Century arms. I believe the rifles were supplied post WWII, prior to the US move into the area when the Brits gave up their southeast Asia empire/zone of influence.
The smiling tiger rifles saw use in WWII, or so I read. When the Japaneseoccupied Thailand and Burma, these rifles were put to use. I have never read if the INA used any of them, but based on the many numbers of jungle rotted rifles it sure seems like they did.