That's possible, a 138 red or 149 is legal in NSW without any other changes. If it's larger than that, then it must be an older modification. You used to be able to register anything, and if it's never been let go out of rego then it would still be legal. Couldn't do it now though.
Even if it is legal, it's not real safe. Converting to a ball-joint disc front end is not a terribly expensive exercise, and gives you much better braking.
There's an article about it in the
Tech Info section.
Hope that helps,
RET