yes its your head gasket.
the reason there is oil in the coolant and no coolant in the oil is that where it broke there is more pressure on the oil side than the coolant side.
mine is rebuilt and still burns oil. check the valve guides while you have it apart. maybe do a leak down first so you can be sure to eliminate the oil burning. its a real pain to check oil at every refuel, as you know.
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1979 4wd Mikado. G200, Gemini 250 Turbo, Clive Cam, Offenhouser Intake, JE Pistons, maXspeeding Forged Rods, Blow Thru Weber, Trooper 5spd, Intercooled