440 block filled water jackets

It depends on how much he filled it, to the top of the freeze plugs?
The freeze plugs are very close to the bottom don't see the benefit if it's not filled up to the bottom of the water pump passage, and It's not really streetable. Also you need to run very wide clearances, piston to wall.
I`d go look at it in a heartbeat, and I`m not really in the hunt for one.
The piston/type, and intended usage will dictate how much clearance u need.
You need to check it out, especilly if it has been run since the bore and hone to .030 . A partial block fill wont hurt if u can keep it cool.