You could do, Golden Syrup is 100% fermentable so can be used as an exact equivalence to sugar. The best way to retain the taste of the syrup is to use it to prime with though.
I've brewed a few using golden syrup or treacle. Because they contain water you need to add more. I found adding around 20% extra worked fine for me. I also found I got a better flavour if I brewed with normal sugars and added the syrup when batch priming. Ended up with a really nice flavoured ale. :thumb: