Realism over 4-bolt vs. 2-bolt main blocks

[nuch_ss396]

I have a question for the group concerning GM's ( Chevy )
use of 4-bolt main blocks on SHP engines vs. 2-bolt main
blocks on STD. & HP engines during the later 1960's & early
1970's.

I was just looking at a thread in another category here
concerning hemi blocks and noticed that these blocks use
4-bolt main caps in the 3 center positions, but only
2-bolt main caps in the front & rear cap positions. I
hope my description is accurate.

Then, I started thinking about the 396, 427 & 454 blocks
and the use of 4-bolt mains front to back on SHP engines.
It has been stated many times to me that you don't really
need to be into 4-bolt main territory unless you are pushing
600+ HP. Is that accurate? If so, why did Chevy put 4-bolt
mains in engines with just 375hp? Is this just a case of
practical, real world knowledge that came about with the
passage of time and engine life analysis vs. what the
engineers of the day thought?

Or, did the use of 4-bolt mains on the BBC factor in
issues like overall engine design ( main bearing support strength )?

Steve