I have had this document in my photography folder for a good 10 years, using it very rare. Reasons are two: I tend to stick with what works, and the fact that I only use two (all right, perhaps three) of these replacements. I do not have that many cameras using weird, obsolete batteries: my Nikkkormats, Minox (the BL with its MR44 adapter comes in as obvious), and a couple of Gossen meters. That is it, and as said, if a solution or replacement works, I stick with it, no need to look for other, more exotic solutions for the obsolete PX27 or PX625.
Anyways, this is the document here; not mine, as I got it as everyone else, from the internet a while ago. It is the work of a guy in Netherlands, forgot his name. He did a marvellous and professional job, approaching the sensitive subject of mercury-replacement batteries for our cameras, meters and whatnot. Some of his contact details are embedded in the document at some point. To whoever you are, sir, a big thank you !