head gasket

One last thing - don't soak the bolts... You need a little squirt on the threads, and a little under the bolt head. If you soak them the oil will run down and get onto the gasket surfaces, and can potentially fill the bolt hole before you get it in and give you a false reading when you torque it. You don't want a ton of oil - you want a thin coating. I don't even "dunk" the threads - I use an old squirting type oil can.
On the power issue - ignore it. You won't notice or miss it regardless of what "it" might be.