[Kahuna]

No, Ronnie.
This is a 4" merc offset ground for a 4 1/8" stroke. Was supposedly balanced, etc., by a shop that said they had built many flatheads and knew how to do the machine work.
What he didn't tell me was that the flathead guy had left some years before.
Here's what was done wrong:
Bore too tight by .001
Crank (rod journals) had taper and one egg-shaped. Had to be reground to .030 under.
Rod bearings set too loose (full floating). Rods had to be resized
Block had several cracks (was magnafluxed by same shop)
Poor balance job
There was more, but you get the jist of it