Yes, the flat side goes against the flat injector face, and the curved/conical side goes against the prechamber. Place one of the washers ("heat shields") on the injector face, it's pretty obvious which way it should go. It fits nice and secure with the flat side touching, and evenhas a little recess to "locate" it on the injector. The other (curved) side doesn't fit properly at all, just floats around on top. Make sure you have the correct washers, the older ones are claimed to interchange but I found they didn't. The old style washers (p/n 617-) have a bigger hole in the middle, the newer (60x-) ones have a smaller hole.
Remember, this had NOTHING to do with my original post & problem, that was the sealing between the head & prechamber, NOT the prechamber & injector. Just wanted to make that clear.
Regards,