Glad your battery swap is working for you Neil!
I mentioned here that I had to put a new battery in a Chevy that had sat unused for a few years.
I too wondered if this was going to somehow upset the engine settings.
I asked around and got all kinds of different answers....."No", "heck yes!", "IDK", "maybe", "bring it in - we'll install it for $140 plus price of battery"

So, bought a diehard of proper specs - and daughter and I set about changing it out.
YOUTUBE was my guide for this model of car. It looked buried -

but was easy enough to access.

Car had sat with half a tank of gas for those years - and in spite of current tales of woe with 10% gas - it fired up and ran perfectly!

Car had

Changed the oil and checked the tires, dusted the interior.
Stig