My understanding is that what you are asking for is technically not possible because the missing wait states don't slow the game down the same way / with the same consistency that underclocking the CPU would, so it's not going to run the game accurately no matter what you set the clock at. If you run the pcb side by side and get it as close as you can, that's as good as it gets for now until someone emulates the wait states. They must be nearly impossible to emulate because the CPS1 is one of the most loved arcade hardware ever made.