Tech info wanted; Lean Burn Dist

Since you do not have a scope, the timing light with two boxes will work. I do not have a dual pickup 6 distributor, the info above suggests 50 degrees advance or 40 retard at crank, for v8. The 50 degree advance window is above the base timing set by primary pickup. The LB control measures the time difference between sensors and subdivide for timing control. The LB timing idea was great, the implementation in electronics at the time was horrible.

Sorry you do not want electronic advance. It will give the grunt off line to burn tires and snap axles, been there done that with my turbo 4. You need to have normal advance or more, without boost, that retards as needed, as boost comes in. Timing varies smooth with boost, not a switch in affair. Retarded timing throws more heat at turbo, but also reduces burn in cylinder centered on power stroke. Proper controlled timing results in a super strong torque curve. It will pull like crazy, and want the load, of up shifts. If you want to keep considering mechanical considerations, try boost retard dash pot on distributor. That might require significant fabrication, considering the need for adjustment compensations.

The EFI controls also play an important part, but that involves electronics too. Having timing and fuel controls on a 3D surface of MAP and RPM with temperature related air density and timing enhancements, is much different than two locked timings on a switch and a carb. You have done such a nice job building your car, then leaving much HP on the table due to primative controls.