What is your budget and what type of power are you looking for?
If you want 250-350 rwhp, consider a gen3 longblock swap.
If you want more than that, consider a built motor. I would put ATS high on that list.
If you don't want more than a decent usable longblock, search the sale forums. I have one I would sell, and there are many others there. You should be able to get one for less than $1k shipped.
Also telling your area would help us steer you toward a local shop, if one exists.