I’m currently building a 454 for my project and I have a set of 6258723 heads and I was wanting to if these heads are worth keeping. I’m looking to build about a 500-600hp engine. I need it to be able to rev to around 7000. I was just wanting to know if these heads are up to the task of what I’m looking to do or should I be in the market for a set of rectangular port heads.