I have a 2012 Jeep Grand Cherokee 5.7L Hemi

Issues:

1) Had multiple misfires, rotated the spark plugs and coils but didn't seem to fix the problem with it rotating to different coils

2) Engine overheated later that month, and oil seem to have mixed with coolant looking like thick chocolate milk, but more yellow and thick, not like some videos of it looking like Cream color milk shake. It came shooting out of the Coolant reservoir and radiator cap. It's Oil in the coolant, but no coolant in the oil.

3) Used the engine block tester and the liquid turned yellow, but took awhile for it to show up as I waited to heat up and thermostat to open and right after it showed up the engine got hot and starting shooting out the chocolate milk again. But the directions said it would show up right away, so maybe did the test wrong?

4) So we decided it must be a blown header gasket, so we started taking it all apart. Finally got the headers out, but didn't notice anything out of the ordinary, no shiny heads or clear signs of cracks?

5) As of right now I plan to buy new heads and head gaskets, and it's cheaper to buy new instead of sending to a machine shop to clean and scrape flat, but scared that it might be a cracked engine block?

Any recommendations?