50s, not 60s. He was a damn good driver and also got some hot shoes like Carroll Shelby and Dan Gurney to run it from time to time. A lot of the body work was made from signs, business and road, that he welded and hammered into shape. Everything about it looks wrong, but it was fast and won a lot of races.
There were reports that Buick sent him "test" motors for the car. But most of the parts came from junk yards and part cars.
What's it got to do with 914s. Nothing. It was called Ol Yeller like the title of this post.
If you want to know more about this interesting car, check out this
LINK.