Salt vs freshwater changes everything. A clean freshwater dumping will do basically no damage if it is corrected quickly. Salt will kill it.

im not certain that he is talking about water contamination. he is talking about a hard freeze sufficient to pop the freeze plugs out and subsequently end up with water inside as well. might he have not cracked the castings ? sure. i suppose if it was closed cooling you could fill it with barrs leak and hope for the best. but thats not the smart play. and there is no way on earth that guesswork from here or anywhere else is going to tell him that answer. he needs to simply make up his mind as to the level of risk vs expense he is willing to tolerate and pull the ttrigger on that course of action.

it aint getting fixed talking about it while it rusts.

Thank´s for your fast reply´s.
When i read your post´s i think the engine-block is junk.
I will run the engine with fresh oil without water to save the rest parts.Next weekend i will pull the intake to search the crack in the lifter valley.
What is the better choice? A new 502 longblock or a 496 HO takeout with a "closed cooling"?

A low hour 496 with closed cooling is the simplest way to go. If the prices are close. You do not have to rebuild, you have closed cooling (big plus!) and it should be a drop in and go.

Just my 2 cents

i think anything with closed cooling is the better deal.... as to the 502 vs 496 deal.... isn't he going to have to buy new exhaust manifolds if he goes the 496 route or am i confused about that...