Shame on Vauxhall, I say. I fitted an Omega 65aH battery in sister's Meriva last Sunday. Earlier I fitted one in a Rover Streetwise, that was a bit of a squeeze.
Transit batteries are good, because they're decent capacity, cheap(free if you're the storeman
), and available with lug or post connections. They fit all sorts of things. I even hung one under the back of my Superminx estate on the same frame as the fuel pump and filter.
Capri front springs fit perfectly in Avenger, Hunter and Triumph 2000 struts, and are a third of the cost of the 'correct' uprated parts. Available in far more combinations too.
Mk2 Escort rear shocks are a perfect fit on a lowered Hunter. As are Ford 'tinilite' wheels. Or 15" 205GTi wheels.
A Capri steering column is ideal for a 100E with Escort front suspension; all that's needed is to weld the Anglia bracket to the column and you're done.