A 261 @ 100% VE, 6,000 RPM needs about 498 CFM @ 1.5" Hg. The 1978-* (largest of 3) DGV is about 332 CFM per pair, so more carb will help.
What 2 X 2 manifold is he using - the original (obs) Clifford with L & R carbs? Or adapters on a 2 X 1 manifold?
