Have you talked with any of the Kent based race engine builders, such as Dave Bean, Craig Chima, Tony Ingram, Jeff at JAE, MWE, Ivey, or any of the others? I know Dave Bean sells press in restrictors for Twincams and BD-series engines, which are sometimes used on push-rod motors. I'm building a similar spec engine for track and street (it's been on my engine stand for a long time, while I work on other aspects of the car) and am not currently planning to run a restrictor. I'm interested to know what you're heard or hear.
Thanks,
Dave