1980 JD 400

I have acquired the tractor I learned to do work on about 30 years ago. THE John Deere 400!. My grandfather bought it brand new in 79 or 80. My dad used it from 1992ish until 1996ish when the engine scattered. This tractor has been sitting untouched in my garage since the last time it moved about 25yrs ago. Other than the scattered engine, it is cherry- Grandpa and dad took very good care of it. My question is........is it worth my time and money to get the beast going again? (After my son and I get our 60 rebuilt [see introduction thread])