Around Tampa the a-parts stores sell something that will seal SOME block cracks depending on how bad it is.
It was intended to seal head gaskets. It's definitely not a "radiator leak" repair.

That might give you a few days to be looking around for another engine.

Some people have good luck with engines from Autozone or Advance.
For some cars it costs around $2,000 and uses some things from your original
engine: oil pan, valve cover, alternator, intakes and sometimes other parts.
It usually comes in a crate that says "made in Japan".

My last one came with the cylinder head already attached and torqued on. That saved me from a lot of work
and also the cost of refurbishing the old head myself.

Let us know what you decide. Thanks.-Bob