Something I learned recently was that Chrysler bought some of Packards tooling when they went out. For the Chrysler Big Block the Big Wigs told the engineers "build us a new engine whatever way you want but this is the bore spacing"
So for 30 years and countless engines,Maxis,Hemis,383s,440s whatever they all have Packard to thank. Chrysler got a good deal on some tooling and they ran with it.