I rebuilt a 390 pulled from a '64 T-bird for my '69 Torino and noticed it had the thicker webbing and cast but unmachined or drilled bosses for side bolt mains. C3AE-D block, cast C3AE-G crank with the 1/8" groove like is found in the early 427's, C3AE-F rods with larger 13/32 bolts as found in early 427's, 390 4.05" bore, normal C4AE-G heads, and drilled oil passages for hydraulic lifters. How common is it to find the high strength webbing and cross bolt bosses in the early non-406/427, 390 bore FE blocks? The books I have show the block casting number to be a 406 so maybe if the cylinder wall thickness was off they just bored it to 4.05" instead of the 4.13" of the 406? Then again my books are not perfect and I find lots of different opinions on casting numbers so just curious if anyone else has used the early blocks with the same findings.