Here is a copy and paste from the RHS site....
"Revised combustion chamber design for excellent combustion thermodynamics and enhanced fuel efficiency"
Now, I don't know if this means that the chambers are very fast burn like the Chevrolet L31 design and others currently available, but if they are, then you won't need any more than 34 degrees total initial and centrifugal, with more available from vacuum at cruise. One of the best guides to
determine the initial ignition timing of V8 engines can be
found in the Barry Grant, Inc. catalog or at their website
under the Demon Carburetor Guide. Typically, they recommend 10- to 12-degrees of initial timing when
the duration of the camshaft is less than 220-degrees @ 0.050” of valve lift; 14- to 16-degrees of initial
timing with a camshaft duration of less than 240-degrees @ 0.050”; and 18- to 20-degrees of initial timing
when the camshaft duration is less than 260-degrees @ 0.050” of valve lift.
So, put the initial where it needs to be for the cam timing, then change your centrifugal advance curve to provide a total of 34, all in by 2800. Then add the vacuum.