book time is about 35 hours of labor. Plus parts--gaskets [$200]and new bolts--[$100] most use studs-[$600]. Should also consider replacing the water pump-- if it is original.
Yes, you have a bad head gasket-- Sorry.
Chevy 04.5 LLY, 2X, shell, XDR, MikeL Heavy duty up-grade, 6spd, TransGo, deep pan, de-badged, 65 Gallon replacement Aero tank, LBZ-mp, Kennedy pump, shimmed, Pre-fuel filter, tow mirrors, BU cam, gauges, GPS, Sirius, bags, custom grille, fender vents, HD trans cooler- Curt front hitch, footwell lights, load lights, Studs, head gaskets.