I suspect you're saying that your cylinder heads themselves have a total of seven cracks (the way you wrote it, it could be the block or intake manifold).
Sometimes cracks aren't really cracks - it might be worth schlepping one to your local machine shop to have them do a quick magnaflux on the head. Might set you back $40-50, and there's no reason to take both heads (if one's really cracked, the other is too - if one isn't, the other probably isn't either).
If you want to/have to replace the heads, consider heads from a junker that you can have rebuilt or buying remanufactured. (To rebuild (valve job and resurfacing) figure $150-$200 each plus cost of the heads. Prob $700 each for reman from a place like rock auto. (If it got that hot, I’d be concerned about the block). Plus parts (gaskets, head bolts, coolant, oil, oil filter, plugs and maybe a timing belt and water pump depending on when they were changed) and labor to reassemble it.
You’ll have to consider age and condition of your X to see if it’s worth it.