ST-1JR ...but it may not end up that way.

[wazkelly]

I'd start with the biggest, thickest strings you can get. If they're too thin, they'll just flap around like over-cooked spaghetti.

I'm thinking a good place to start would be E - 0.130, A - 0.100, D - 0.080, G - 0.065. Basically a 5 string set without the 0.045 G string.

Good suggestion Muzza. Just hope an 8 year old girl can get her tiny fingers down on such thick strings without too much trouble.

[Muzza]

Good suggestion Muzza. Just hope an 8 year old girl can get her tiny fingers down on such thick strings without too much trouble.

She's just got to get the strings down to the fret. Any thinner will flap like, well... They'll flap a lot.
She'll be fine.
At the end of the day, it's a starting point. I'm pretty confident I'm on the money though. Have you see the size of the nylon strings on those uke basses?

[wazkelly]

Nah mate, never seen a Uke Bass? Anything shorter than 34" scale on a bass makes me feel a bit cramped these days. Mind you my very first one was a SG copy and suspect is was 30" short scale but that was about 37 years ago and my memory has faded a bit since then.