Magnums had better compression ,cams, valve springs , timing chain, intake , exhaust manifolds as stated above nothing that you would use anyway .
The performance engines were known as Magnum in Dodge , Super Commando in Plymouth & TNT in Chrysler
Any 440 with the thin 1" thick Damper is a steel crank , after 72 most were cast with a 2" thick damper . This is not an issue if you plan to stroke it .
Early blocks did not have the extra casting rib on the outside at head bolt depth , I used one of these block in my Duster & raced it for 9 years shifting at 7200 rpm with no issues but it si better to use the ones with the rib .
With the cost of stroker kits & new parts the block is about the only part used anymore .