I have an old deepdish sports steering wheel. It's trimmed and leather. the leather has perished though and the padding has seen better days. Two questions;

1. where can I get some new padding for it?
I like something firm, like hard foam rubber. Who sells it in Sydney?

2. How hard would it be to stitch it up myself?

I don't know about the foam. But I bought a cheap wrap around vinyl imitation leather steering wheel wrap around for my Beetle. It came with a string which you used to wrap around the wheel like a ballerina shoe strap.

It actually looks good and it only cost $5 from Autobarn. I purchased it during a sale.

Its held perfectly well for over 10 years. And has no holding problems.