Because it's not a 2G head
It's a 1G head, the car has that and a 6-bolt bottom end in it
It's got arp headstuds and when I had it, good valveseals and didn't burn oil or coolant, and had recently had the timing belt and water pump replaced. Not something I'd jump into taking apart.
Mara/Shane's car makes 480whp on DB's dyno and 560whp on MAP's dyno with a stock, unported 6-bolt head with some basic springs (crowers) and hks 272's.
Another great route is just keep the s-afc and do cams, but sounds like dsmlink is on the way already