Alan, I’ve done internet searches as you have suggested chasing something similar to the original Lucas fitments, perhaps for no other reason than that I want to find something similar to the original Lucas fitment! The ’85’s have a narrower battery tray than the ’88 so they are less tolerant of the base hold-downs of modern batteries. Not a problem to shave them off, because the goal is to be able to start the car so it doesn’t really matter.
As for the venting, I’m reluctant to use non-vented batteries. If General Motors still vent batteries that are installed in the boot of their larger cars then I’ll take that as a hint to continue the practice.
Your comment is appreciated, though. I guess I’ll fussiness back where it belongs – in the not important basket.