Dude gives up easy, huh?
I wanted to ask him how many guns he was talking about.
First he says his dad owns the gun, then he says the gun was willed to him by his grandfather.
An executor, in Ohio, is a legal appointment by the Probate court. If the will specifically names the OP, then the executor should not be committing a criminal act by "providing" the gun to the OP. A lawyer will be along soon to correct me, if needed.
As long as the OP has never given up his possession of the gun to anyone, since the time it was willed to him, he should be fine to have it.
He couldn't use his dad's gun unless his dad was with him, otherwise, like eye95 said, his dad becomes a criminal.
How to transport it? I would guess that normal, non-CHL transport rules apply. Unloaded and in a locked box, with ammo stored separately.