After much swearing, looking, head scratching. I decided to drill out this connection to get a better look. It ends up to look much worse than it really is. Where the parts actually mate, the sealant is very thin. however, by drilling/punching all the rivets out I'm quite concerned that the rivet holes are too opened up/sloppy.
Being this is a major connection/stress point for the engine. I've made the difficult decision to abandon this fire wall. I will have to order a whole new firewall, but it isn't cheap and I have no money for new parts right now.
This build is put on hold for a while.