hey guys i just bought a 85 6.9 with 144000 miles

. the truck has been sitting for 11 years. the p o said he was getting engine oil in the coolant which i found is true after filling radiator. i was wondering if anyone has ever seen this before or know what is causing it. im guessing its pry the oil cooler or possibly head gasket (hopefully oil cooler) the oil is clean no water in oil. also since it hasnt ran in 11 years and has 11 year old fuel in it is there anything i should do before trying to fire it besides droping and cleaning tanks, flushing fuel lines, filling new filter with some power service and flushing water seperator?
thanks for your help