Both good finds, I hit these up as well:

1) Summit Lock bolts - never used this style before so I'm a little hesitant to toss these into a street car where the header to chassis clearance is already tight

2) Hedman - larger 6pt head (7/16) vs 12-pt (3/8) on the ARP, there are a couple of tight spots on this install, like the #7 cylinder, where I literally need every tiny little amount of wrench room, I say this because my old headers were using the shorter 6pt Hedman bolts and it was such a PITA to tighten up a few of these bolts

I'll fire off a quick inquiry to ARP next.