Head gasket????

[Cammaxon]

This is off of my DBP invoice

"Car has a lot of oil smoke under boost/decel.
Car is overly prone to knock. Could be from old gas, too high of
compression, too much oil getting into combustion chamber, turbo
design, or something else. Turbo wants to boost creep. Might be
pushing coolant during boost from head lifting or partially
blownheadgasket. We swapped on a different radiator cap and
topped off coolant system."

Whats it take to replace the head gasket?

If DB reads this? Is the car in good daily driving condition or should i look into replacing the head gasket? turbo?