No, it does not make 1,000hp. No, it does not rev to 10,000 RPM. This engine, which you are now ultimately confused about is not an engine that was raced at the Indy 500 rather it is a production engine from a Maserati Indy, which was a 2+2 the company made from the late 1960s into the middle 1970s. The plant is a wonderful dual overhead camshaft V8 engine that displaces 4.7L has a triplicate of Weber carbs on top, and makes just shy of 300hp at only 4,600 RPM. This is one of 364 such engines made between 1970 and 1972 when the Indy 4700 was offered.
The video description is short but it says that the engine shop got boxes of rusty parts and between reconditioning what they had and making new stuff, they got a working engine out of the deal. There were only about 1,100 examples of the Maserati Indy made between 1969 and 1975, which is kind of a shame because it is a really good looking car. It weighed about 3,700lbs but with a 5-speed stick 300hp was certainly sporting for the time.
This is one of those engines you never see or hear very often. We figured your ears would enjoy it.