This isn't even a ballpark figure 'cause the ballpark doesn't exist, but just to give you some idea I go by the following:

Really rusty outside, carb missing (or other openings for water to get into the engine) and stuck (won't turn over) $0

Ran when the truck was parked umpteen years ago - $0 - 100 depending on condition, particular model and how bad I need parts.

"Ran when pulled out and stored inside - engine is complete and all openings covered" $100 - 250

I get to hear it run, no blue smoke, no funny noises, etc. $250 - 500

Block has been disassembled, cleaned (hot tanked), magnafluxed for cracks and is guaranteed returnable if serious cracks are found - complete engine with all bolt-ons - $500 & up


Good luck with your motor.