Yes it was real, yes there was such thing as class A racing, and yes there was a version of the 4age(or at least thats what it was based on) that reved to 11,000RPM and produced about 250HP.
No, you cannot get one. They were RACING engines. very exspensive, very hard and even more exspensive to maintain, and there weren't that many made. Plus they wre designed to run on race grade fuel.