GN heads suck anyways, like said use vortecs or you can find aluminum heads for around 500 if you look hard enough. i have a set of bowtie 23 degree heads for my new turbo 4.3 sitting on my engine stand
__________________
94 s10, 4.3l v6, sectioned HSR, twin t3/t4's, bowtie heads, lots and lots of custom parts