'MEL types are true big blocks and are heavier'
That is one way to look at it and a good way.
MEL's are same family as Super Duty truck engines.
https://en.wikipedia.org/wiki/Ford_Super_Duty_engine
'Angle block OHV V8's' like the MEL.s.
Both came out in '58.
Biggest Super Duty was 534 cubic inch.So.MEL's are little brothers of Super Duty's.