I found a 352 in a ’64 Galaxie on E-bay for $100 in San Diego. You could probably find something similar in your neck of the woods. The Ford guys here will let you know what interchanges, i.e., other engines may just bolt in.

Roadmaster has a 352 long block assembly for $1495 – but you’ll need several hundred more to finish the job.
Roadmaster Engine Corporation
759 Bradfield, Houston TX 77060
800.447.9899

As mentioned above – free may not always be a good deal. If you want to keep it, it will mean some money – maybe more than you want to invest in this particular project. Foggin’ skeeters may be the ticket for this one or you could run some solvent through the engine and fill the crankcase with 40W and “pass the gift along” with the disclosure that it’s real tired.

Regards and Welcome to CHR,
Glenn