stuck engine on a 79

hi everyone. new member here. i'm looking at a 1979 mgb that hasn't been run in 7 years. the oil on the dipstick looks clean-no water present. with the gearbox in neutral, we tried to move the fan, it has one mechanical fan. well, the fan would not budge one iota. pulled the plugs and three were really badly carboned up, so in went pb blaster into the cylinders. i plan to return in 5 days and see if this helped. meanwhile i have heard this could be caused by a frozen fan clutch or even a frozen water pump.is there any way of knowing. a new pump and fan clutch would be a better scenerio than a stuck engine. any help greatly appreciated as i'd like to make an offer for the car. the body is mint. thanks.