heating the block with ice inside still is not a good idea, very hot vs very very cold = cracks.
if something was to crack while being frozen, it would have been a freeze out plug popping and coolant/water hitting the floor under the car. as thats what they were made to do, hens why its called a freeze out plug.
the upper intake may have blown as well, that could be where the water got in the oil as well. you can take the tb off and look inside the intake to see if its wet inside. it should be bone dry.
but before you think of doing a top swap, test those 2 items first. make sure the block is still good.
