Advice on a different size of Christmas Pudding

Hi Linsey, this year I'd like to make some smaller Christmas puddings. I couldn't find any pudding basins as small as 175ml, as mentioned in the Christmas book, but have got some that are 325ml if filled to the rim. How long would I initially steam them for? And how long would they need on the day? Also should I pack them right up to the rim or leave a bit of a gap? I can't remember how full up last year's 1.2 litre basin was when I filled it.

Thanks a million,

Sara