Need a plan - component selection for restoring 68 340 that runs on 91 oct

Paul G wrote in another thread
"I have been fidling with my 72 Charger with an iron headed mild built 360 for 5 years trying to control engine overheating, detonating, hesitations, poor idle quality, lack of power, etc."
What we are trying to avoid
measure twice- cut once
Bottom line is that flat top pistons in open chamber heads leave torque on the table (not necessarily top end hp but that rpm range when the engine is working hardest)
so do long lazy cams of which the stock 440 HP and 340 are among the worst not nearly as much area under the curve as the penalty of long duration imposes
glad your octane is consistent nm out here in CA it varies all the time and especially "summer blend" vs winter blend"- gotta build for worst case for pump gas