First, I am recalling fond childhood memories of my big brother's 60's Austin-Healey. Thank you!
You can use the CTEK 12-Volt Universal Battery Charger # CTEK56353 on your positive-ground vehicle. The instructions included with the charger specify (on page 5) how to use this product on vehicles like yours that use a positive ground.
You will connect the negative charger clip (black) to the negative battery terminal. Connect positive charger clip (red) to a good metal engine ground away... view full answer...