Blown head gasket or just air in the system

I changed the thermostat have yet to burp the system but before that there is heat at high speed or during acceleration. No heat at idle (even at operating temperature) engine has overheated before but that seemed to be low coolant. At that time I did add coolant but did not burp it.
No milky sludge or froth on the oil cap or rad cap. Oil is black but have yet to get an oil change on it.

I have read a lot of fourms and watched every video out there but no scenario was exactly the same, just trying to make sure before I fork over a bunch of money on a head gasket.