273 Charger Tear Down-Head Gaskets/Valve Seals

I used a 9/16 crows foot? Bought it from TMM.
Always planned to keep this one all original especially since it's the hipo 273 it came with.

Struggling with the manifold flange bolts right now however.

Any ideas on how to get a wrench on top of the passenger side rear flange bolt head? It has a keeper/retainer on it I suppose just for this, but it's not doing what it's supposed to and I'm just spinning the bolt.