The more practical way to get the hypothetical Model 19 running again without the correct barrel would be to install a one piece Model 14 or 15 barrel. I nave seen a Model 19 with an old skinny Model 15 barrel installed and another with a Model586 barrel. The L frame barrel was used to add weight. It was the owners idea of an ideal .357. He did not say if the original barrel cracked. An L frame barrel has to be recut with the smaller diameter thread. If you had a Python barrel you could make a Smolt.

In reality the cracked 19 would probably be deliberately fouled to hide the crack then sold to an unsuspecting buyer. That happens more often with bulged barrels. This makes buying the only gun in the store with a dirty bore and low price risky.