After some advise, and a very brief bit of poking around at Games Empire on Saturday, I decided to at least start (or play some more) with stuff I had on hand. So, I worked out some of what I’d need using either 2nd or 3rd edition GURPS. (I looked briefly through my 22 year old 3rd edition book, but discovered that its pages were falling out, so I reverted to my older – I think 2nd edition – books).
I’ve updated the page on my site with this detail at the bottom. I still need to do the races for the cats and dogs.
And I still don’t know if there is any chance of this actually ever getting played but at least I’m having a bit of fun.