That's not true. If you bore the block to .080" over and successfully use it until it needs another rebuild the block can be bored out and sleeved. You can bore a block out completely into the water jackets and sleeve it. In fact many racing shops bored flathead Fords out completely and then sleeved the bores so that the cooling was even on the cylinders. The even thickness of the cylinder walls made the flathead Fords run much cooler.
What you have to do is use a thicker sleeve. Any good automotive machine shop can do that. The largest you could safely bore a flathead Ford was 3 3/8+.030" which mine was bored to and with a 4" Mercury crank it was a 291 ci engine. At that point the cylinder walls were very thin and it would run hot. The safe way was to bore the walls out completely and sleeve it and bore it to what you desired. I believe at that point it was 3 1/2" max. and with a Mercury 4" stroke crank it was a killer torque engine off the line.
I was 17 years old at the time (summer of 1958) and bored my own block with the boring bar I now have that my uncle used in his speed shop and I built my own flathead Ford engine with. Bored, stroked, relieved, ported, polished, 3/4 street cam (high torque low end), 3 two barrels on Edelbrock manifold, Fenton cast iron headers Eldelbrock heads flycut and domed for popup pistons, special modified distributor, in a 1951 two door sedan. 0 to 30 in 3.2 seconds, 0 to 60 in 6.8 seconds, 0 to 100 in 13.7 seconds and it was a street racer and the flood of memories come back when I call for them.
Those were good years and I bring them to mind from time to time.
