I'm guessing the original poster realizes the 8-10K rpm Chevy motor aren't $7K.
But I feel there is a turning point here. And I feel for his dilemma... Spend $20K or whatever on a Chevy motor that you know will do the job and you know the resources to achieve it. OR go hunting around and spending $20K experimenting to see if you can get that same job done. Beyond the money, it takes a lot of farting around. If there is no one out there doing real close to what he is doing, he's taking more of a chance. You can spend $20K+ on a motor and have it blow the first lap.
Sure in theory you should be able to build something comparable. But race proven is different than theory.
Not that "proven" means the Chevy or Ford is a better motor. Many times that's just a bunch of other people who broke parts first at your track until they figured stuff out. Somebody else was the guinea pig before you.