Edelbrock mt-5 for 318

All-par states that 318’s were high swirl from 1986 through 1991. I have read somewhere else that some of the late production 1985 roller cam 318s had 302 heads as a mid year change. They are prone to cracks between valve seats. Installation of hardened exhaust seats seems to be a pretty common repair. It.s not a bad idea during a valve job either because the factory seats are induction hardened after they are cut and are really just surface hardened. A significant cut will remove all the hardened material. There are several on this forum whose opinion I hold in high regard who say that more often than not the heads with cracks between the seats rarely leak and are still usable, cores should be pressure tested regardless.