Remove the legs from the top and drill four holes through the base and mount that on a tall wooden box or cabinet. My saw is the same, but I mounted it on a pre-fabbed tall cabinet and attached some slats to the bottom and then added the casters. My table is a little above belly button height, just right for me.
I hadn't noticed the truck before. That is great! Is it rideable? Is your grandson doing most of it? Great learning project.
I recall one of the first nifty toys I ever made was a toy piano for a production of "You're a Good Man Charlie Brown." A friend was directing it. It had moving keys and what I'd have to call an "infant" grand shape. Didn't play, but the curves were just right and you could stand on it. It was probably the first nice plroject I ever made. Still remember it well. By the way, the friend's name was Melody Ashburn, and thinking back, she looked very much like you, red hair and all. She was a buddy's girl friend, not mine.
The more I do, the less I accomplish.