There should be a gauge given (like, 20 stitches per 4" or something) for the pattern, that is the most important thing... you want to find a yarn that has that gauge.
So you'd probably need to stick with light worsted, or you could use another weight and recalculate some things.
I think you could also use sport weight and knit with 2 strands or it held together to get a worsted weight.

Hopefully someone that knows more will respond.