I think the amount of webbing left inside the spoke makes a difference, at least to my non engineer eyes. IE leave some web don't take it all the way out to leave just flange. Or two shorter slots instead of one long one. You know the old conservative route. These were early motorcycle mags, casting quality, engineering, testing, and field experience all contributed to the later, thinner, wheel designs. Hard to overstate the danger of wheel failure. Minor point; as an experiment I busted up a bent Honda front mag with a 12 pound maul just to see what it would take. It took a lot, I whaled on that sucker a LONG time before I was able to bust it up. It bent and deformed a whole bunch before cracks formed and parts broke off. Like the airplane guys say when making changes; just remember YOU will be the test pilot. If you do this you have added a regular inspection area to your bike.