Bridge circuits don't care about mercury cells, I think.
While my ancient Praktica LTL wants mercury cells, since it is a bridge circuit - usually identifiable by a meter needle "wanting" to be centered in a fixed circle or whatever, actual voltage is not critical, except perhaps in terms of ultimate low light sensativity. Finding a silver oxide of the appropriate size is the problem.
It is amazing how long mercury cells last! I have an ancient LaFayette Radio (anyone else remember them?) CdS meter. I may have replaced the mercury cell once after buying it to replace a dead Sekonic Microlite meter sometime in the mid '70s I think. The cell still hits the BC mark. Gotta be perhaps 30 years old?
I've often wondered if a solution to the mercury contamination problem would have been a huge deposit on the purchase of a mercury cell, at least partially refunded when the cell was turned in for reprocessing. The huge deposit would cover the cost of the exchange program. Thus my Bulova Accutron series 214 Spaceview could be completely authentic.