Does this look okay? want to do a 360 mag swap

Can't that type of discoloration be caused by overheating???

Treblig

It could but time and sitting looks just like that with a difference.
See the tops of the rocker edges, how they are blacker looking where one might think it could be caused by overheating?
If it was heat that caused the discoloration everything below that should be black also, not just the tops of parts.

I'm not saying it doesn't have a cracked head or some other problem that caused overheating, just that I wouldn't be to concerned about the looks in that pic.
I would spin and test oil and compression though for sure before I decided.
Seeing the pistons would help a lot also, but sometimes ya just gotta make as informed a decision as possible under the current circumstances.