If you go back up this thread to the cutaways, I believe with a .060 cup or locator you could run 750 open pressure as far as the spring seat is concerned. That is a load on ANY aftermarket heads stands. You can look at the structure under them but that is a lot. You could helicoil them ( no big deal) and help a little. Heck even the VIctors had trouble with that with that kind of spring pressure.
Todd