[sdiy] Reverse-polarity NEMA-1 plug or cable?

[cheater00 .]

Hi guys,
I am looking for a fairly esoteric cable for my Brüel & Kjaer 2423. In
the back it has a 2.9 cm diameter hole which is maybe 1.5 cm deep,
with two rectangular blades that are 2cm long. They're the kind that
are panel-mounted and might have turned actually, but currently they
are in an exact NEMA-1 configuration, down to the milimeter. So I
think this is a receptacle for a NEMA-1 extension cord, which should
plug in and provide power. Except the wall plug should be a Schuko..
and the cable should be rated for 230V of course. I think the plug
might look something like this:

http://www.sayal.com/images_c/PQD-1203.JPG

except there's no ground lug, and the two lugs are centred, not
shifted up. So maybe a little more like this:

http://www.goodpex.com/d/file/LED_Technology/LED_Basic_Knowledge%26Glossary/2010-07-26/1a5ead4ee80d16b545a1bf520f1e5831.jpg

I would be thankful if anyone had a tip.

Also, I wonder if a cheap alternative could be a simple rectangular
NEMA-1 plug, like those Korg cables. Maybe the actual plug was
rectangular, but a circular hole punch was used for ease of
manufacturing.

Are any NEMA-1 plugs rated for 230V?

Cheers,
D.