The pilot & main jets are marked with the size but it is not stamped in, looks laser etched?
I've measured up the supplied unmarked needle, it corresponds with Keihin number CGM, or R1371N. The R1371N was a needle supplied stock in the '87 TRX250R and an option for '88 KX500 and '88 & '89 KX125 & 500.
Haven't determined the slide cutaway yet, can't find any information on how to correctly do that yet :-)