A smaller Preserved Ginger Cake

I made Delia's Preserved Ginger Cake using a 10" round sandwich pan instead of the 8" x 10" tray called for in the recipe. Using the cooking time (45-50 mins) stated in the recipe, the cake turned out perfectly.
I would like to make the same cake in an 8" round sandwich pan, and have calculated that two thirds of the recipe would fill the 8" pan to the same depth achieved when I used the full recipe in the 10" pan. I think the cooking time would be about 30-35 minutes but I'm not confident about this, so I'd really appreciate it if you would let me know what you think the cooking time should be.
Thank you very much.