Well Kid, You're WAY ahead of me in L6 Technology. I'm still running the XXth Century style 292 at .030, w/Clifford headers, Offy intake, Edelbrock 1404, 4 bbl 500 CFM, Crane 260H cam, SM465, Centerforce clutch, 12 Bolt 3.73 Eaton posi rear. I had a Pertronix II set-up, but it killed itself above 3000 RPM [60-65 MPH] so I went back to a DelcoRemy Point-triggered distributor. Now It runs great.
It's my second build, but then I get about 25 years to the engine, so some things [like skills] get rusty.
Can I presume you are familiar with the websites listed below? --
www.inliners.org
www.stoveboltengineco.com
www.cliffordperformance.net
www.12Bolt.com
To get to basics, it sounds like you have a fuel flow problem.
Are there any long stretches of rubber fuel line in your system? How many filters? Does the tank have a fuel return system you could be using?
You might have to bump up to Dash-6AN lines all the way thru. With that kind of fuel requirement you're in SBC 5 Liter [301 CI] territory. The OEM 5/16" fuel lines may be restrictive.