WRONG! Headgaskets on those aren't what they seem. The #1 problem is the aluminum block, when you take the head bolts out the threads come out with them because GM in their wisdom didn't sleeve the holes just tapped the block instead. Consequencely, ALL the holes must be drilled/reemed, retapped and "timeserts" installed basically they're like a solid heli-coil. The TIMESERT kit cost me just under $400 if i'm remembering right.
I've done 2 northstars at my shop, GOOD TIMES
On the good side, I'm sure it's already been done since his motor has been rebuilt twice