Triumph of Burbank - a very famous Triumph dealership supplying the race trade - built "factory choppers" like that. They were marketed under the name Sunset Tripper and sold really well in Los Angeles. Ads were in Big Bike and Choppers magazine every month.
This could be one of them.
It looks like it could be. From googleing Sunset Tripper I found some pictures of one on RAGBAK's blog that is similar. There is also a review of them from "Road Rider" in '72. The guy is a little finky but it's an interesting perspective.