Finally installed a new optima starting battery to go with the auxiliary optima yellow top. Everything fits really well, but did have a few hassles.
The existing earth lead was not long enough so had to replace that.
And then I pulled too hard on the positive lead to the starter solenoid, which caused the lead to come lose on the terminal and when I went to tighten the nut, the thread was stripped on the post on the solenoid.
Then I dropped the bloody nut and couldn't find it, so found another with the same thread, packed a couple of washers into it, and now it is nice and tight!
Then it all started and ran like a top!