cracked magnum heads

as many cracked Magnum heads as I have run across, the cracks between the valves can't be thru, as the engines they were off of all ran when pulled...… I never have, once they have been deemed cracked, but they were fine before eyes got laid on them..... couldn't you just cut them for new seats and get rid of the cracked material in so doing?
I have 2 sets of Magnum heads at the machine shop now that are headed for their junk pile as a result. One of which came off of a 200K mile engine in a 1 owner truck, that had been known for sure to have never overheated, from new.
the guy replaced them with aluminum "just because" he made a 408 out of it. NOT because of any issues.