Wasn't mine, it was an old 78mm bore twister top end on 4 mm. Pre small block era, pretty much almost a T-Rex. I was gonna buy it. I rode it, tweaked on it, but after a whole day I just wasn't feeling it. This was the experience that made me finally start considering 10 mils for my set up.
No idea if it was balanced. I asked and he said he bought of a dune guy from Oregon on Planet sand back in like 09....
I just think there is a broad spectrum of workable combos from over square motors to under square motors, but if you flirt with an extreme sized piston in relation to the crank, I think you could be asking for trouble.