Each successive cubic inch change in the life of the SBC has always been based on improving what was previously done. I'm sure the 283 evolved from the 265 however they don't share the same casting numbers based on my Chevrolet Parts Books (not the internet).
As mentioned above the 265 only had two different casting numbers, 3703524 (55) and 3720991 (56 & 57).
The first 283 (a one year block with no side motor mount bosses) was casting number 3731548. The max HP in 1957 was 283, 1958 was the first 290 HP 283 offering by Chevrolet.
I believe there were at least three different 283 casting numbers in 1958, but that's another story for another day...
The 1957 block 3731548 was truly a one year block. As soon as the 1958 blocks came out they became the replacement engines for the 1957 cars and trucks and would be listed that way in future parts books.
Mike B
