By my reckoning, 42 pins is 5% extra... it might be amusing to try to see which pins are inputs, outputs, power supplies. There might be ways of doing that - I'm thinking resistance, capacitance, diode nature.
DIP-42 is not rare but also not common. A quick Google search turned up an answer that ...

Wish I had known that Chinese are into that 8/16-bit stuff. I knew about component counterfeiting in general, just never figured a hobbyist CPU would be such a target.

Yeah, we all heard those. I bought chips for stupid good price. Each cost me $2 apiece shipped, on eBay. From China, naturally. Listed as new W65C816S , but very used with blobs of solder. And it only gets better from there.

I bought five of them. Three arrived in a DIP-42 package. I am not aware ...