A few weeks ago, my SP 350 overheated on the highway (crappy radiator), and got to 260 on the gauge. I pulled over, shut it off. Took a while but it settled down and didn't over heat again on the way home. About a week later, I started the car up and drove to the gas station to air up the back left tire. Started with 1 pump, ran perfectly fine and smooth. Started it back up afterwards, and the engine was shaking and stuttering. Thought it was just some bad gas, so I floored it while driving and it went Ba-WHAA (pause...) AAAAA (pause) POP POP AAAAA and it had no power at all. Took it home, gave it a compression test, #1 was 90 psi (was 170), and 3 and 5 were 0. I stopped testing after that. So, this leads me to believe the headgasket blew out between 3 and 5, and I guess partially 1. The engine still idles fine, save for a shimmy here and there (I guess when those affected cylinders fire), and if not flooring it, still drives "normal". it feels like it's running on, well I guess 6.5 cylinders. My question is, how easily to SBB deck surfaces and heads warp? It only got to 260 once, and it still idles ok and if just putting around is ok as well. No coolant in the oil. Any input is appreciated.