I'm probably not a good guy to ask about batteries. My actual Yashica TLR is a Mat 124G and the meter seems rather intermittent, essentially not working. I suspect it has something to do with the contacts that turn it on or off when the viewfinder lid is raised or lowered, but I haven't had time to dig into it. I own a Gossen Digisix and a Sekonic L508, so I just meter separately (or use Sunny-16). I own (bought for another device) one of those Cris Camera adapters that holds a smaller silver oxide cell and puts a Schottky diode in series to replace the old PX625 mercury cell, but I've not done anything with it to judge its effectiveness. My originally intended use didn't work out because a circuit board mounting thingy couldn't keep the adapter in position.
There have been some occasional discussions about battery issues on the regular APUG forums, but I've not experimented (yet). Zinc-air hearing aid batteries with an O-ring or other spacer is one possible solution to get approximately the original 1.35 volts. Supposedly you can just uncover one of the several air holes and the battery will last longer(!) Mayhaps some day I'll have a bit of first hand experience to offer.
If your CLA included adjusting the meter to work on 1.5 volts, I'm thinking there is a button cell of the same dimensions as the old mercury cell, but it may not be as readily available in silver oxide, alkaline being more common.
DaveT