Invert sugar also has water in it. As in baking, you can make a 1:1 substitution by weight - the only issue might be the flavor that honey will add, but that depends on what you're looking for in the final product.
If you want to make invert sugar, you should add a very small amount of cream of tartar or another acid to help the inversion along.
As SnickASaurus mentioned, I think 1/3 regular sugar wouldn't be too big a deal in place of the invert, but if you want, post your recipe so we can be more certain about that.