Does anyone know where I can get a rebuilt/remanufactured/crate/used one?

It appears my head is cracked in two places. Since my engine has 155K on it, a lot of mechanics I've spoken with believe it will be useless to rebuild my engine at this point since the tolerances might be too off. They said it's not worth sticking a new head on there with the bottom end not being rebuilt and having as many miles.

Consequently, they said even if I do rebuild my current engine -- it will cost around $6-7K ... so, it might be cheaper to buy a used engine, rebuilt/remanufactured/crate one.

Where can I get one of these so-called engines?

Any leads would be appreciated.

Thank you,

James