That's surprising. But Konis have adjustable rebound damping. Bad
design means you have to unbolt the top mount to adjust them, but
they ARE adjustable. Had no problems at all on my 75 Bay with Konis
set to pretty stiff (suspension otherwise stock), including rough
roads. Haven't fitted my new Konis to my Caravelle... well, it's
engineless, so why bother!

I would not expect changing springs to make any difference to
sidewind stability on straight roads.