Yes, an 8/32 screw would be the same as a USA Chicago Screw size, but Dwayne tried it per the previous post and it didn't work. Every USA Chicago Screw I have ever seen or used is 8/32 thread, however there are some imported conchs and I suppose Chicago Screw knock offs that use metric thread sizes. The screws are NOT interchangeable between the USA made goods and the imports.
I have frequently purchased 8/32 screws from the Hillman display at hardware stores when I need longer (or shorter) screws than came with the Chicago Screw.
Further, I will be glad to send you one or a few Chicago Screws for just the cost of mailing which will be much more than the screws are worth considering a 5X7 padded envelope plus the $3.50 Fist Class postage would come to about $4.
I think your best bet would be to take the sheath in hand and go to the hardware store and try the screws. When you find one the right size and length, then buy it and the matching nut and away to go!
Paul