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v20-16, z80-20 and chip counterfeits

I've got a 8088 cpu blank, and a z80 cpu populated.   I bought a 10 chip lot of z84c0002pec's from ebay, and was a bit horrified when I got them to find
that they smelled of new paint.  identical fronts, but the backs showed different countries (indonesia and phillipines), all with different mold imprints.

obviously shenanigans. 

so, I wired up a 20mhz test rig for the z80's, using a derivative of dunfield's no-ram monitor (i disassembled it and added a lot more code), and not a one tested
out at 20 mhz.  one limped at 16, 2 ran at 12, and the rest were good at 8.  all tested as cmos: the out (C),F instruction sends FF, the nmos sends 00.

for 15 bucks, I got a bunch of mildly useful z80s of unknown actual characteristics.

anyhow, now i want to build the 8088 board with V20's - NEC has a part number for dip-40's at 16mhz.  70108hcz-16.  lots of them available on ebay from china.

any experiences here before I become the ebay counterfeit chip crash test dummy?