John,
Sorry, but I don't have any pics of the truck block notches. (or externally) Maybe you might find one on the 348-409 site? The notches are very deep, maybe 1/4", so overboring won't do much to reclaim compression. You'd have to bore it almost .090" just to begin to cut into the combustion area where the notches are. That area is rough machined and a larger diameter than the finished machined cylinder wall.
The pic I posted is of a '62 409hp block (.057" over). IT was only to illustrate the swept part of the cylinder vs the wedge chamber above it.
Verne
