Never unlace a wheel without removing the freewheel first. It will have to be relaced now to get it off.
The freewheel threading is close enough for Campy/Shimano etc that it doesn’t matter (1.37"x24tpi IIRC) if you use a Regina/Suntour/Shimano/Campy freewheel.
It’s not a lockring, it’s a multispeed freewheel that uses a 2 prong tool to remove it. Suntour went to a 4 prong because you generally couldn’t apply enough torque to get it off without destroying something. The splined interface used on later freewheels was better still.
I might have a look around for the prong tool, I’ve seen something like that before. Yeah, the tip on removing cassette before unlacing, but the back wheel was close enough to destroyed when I got it!
That explains another set of low flange hubs, Campy with Regina, cool thanks for that.