Can't remember what I paid for my 5.7 that had a dropped seat. Pretty sure it was under $1000, but over $500. May depend on the internal damage. I had the bad cylinder sleeved (wanted to reuse pistons to keep cost down, otherwise could have probably just bored them all out). Tried to salvage the head, but ended up going with a reman for a few hundred. Got a free replacement piston with some other parts. All in all, probably about $500 to fix the damage for what it's worth. I also did this a little over 3 years ago, so I'm sure prices have changed some.