Those 50 year old Macs and others were built in a time of basicaly old growth cutting .7 foot Douglas firs and red woods on the left coast and 4 foot oaks in the heart land.Powerful ,heavy and cost a bunch of money.Well there isn't much of that sized timber done these days and those big old torquers have been replaced with lighter faster saws.Just the way things have evolved.
The big old oak slayers are a hoot to run for a short period of time but the novelty wears off rather quickly .Been there and done that .