Sudden Power Loss (opinions)

I was doing a brake stand in my 68 barracuda 318 4 barrel with 200k plus miles. While smoking an old set of tires the sound of the motor changed and the power loss was instant. I went home and checked the compression and although slightly lower then factory 125-135 across the board I didn't notice any other issues. It has been starting to run warmer then before. Now on a 15-20 mile ride it will go up to 200 when it was staying at 180. I thought head gasket but no water in the oil or exhaust in the coolant i used an coolant tester. Oil pressure cold 65-70 once warmed up and at 200 or so at idle 30 but while driving back up to 60.