There is a guy in australia that "SAYS" he has gone 60 thou with sleeves. Personally I can't see the point in waisting the money on the 1.3.
So, it is possible to do it.
What you need to do is take your block to a mechanical engineer to bore it out to the specified thou you want and have them make the sleeves to suit. You might also want to note that it will be hard to get pistons to suit. They will more than likely have to be custom fabricated.
Ring some people and see what they can do for you. I have no idea as to the level of mechanical engineering knowledge you have. So I'm not sure what work you can do yourself. Oh and there won't be anyone in the world (that I know of) that will sell the sleeves "off-the-shelf" to you.
just some food for though and my 2.2c worth. In my 1.3 (before it blew up) I had a 30thou over bore, larger pistons to suit, shaved head, ported/polished, inlet tweeked a little bit, isky cam and K&N....It went like a rocket.
Slowly building a beast.
"If it's too hard or you're a pussy, give me a go at it"