Magnum replacement head ?

These heads were on a 360 magnum I have. It's has the melt away plug insert on head. I assume these were replacement heads and had those melt away for warranty purposes. Meaning if they melt they can say it over heated and not cover it. It was suppose to be a replacement engine I believe not just heads. Question I wondering is these heads any better to the cracking issues or no..obviously I would need to have them checked. Can you visually see the cracks sometimes between the seats. 20210720_111419.jpg 20210725_111048.jpg

20210725_111538.jpg