ignition timing

[Squash]

Does anybody have any suggestions for ignition timing on a 454 with
digital projection?  Performer intake, tube headers, 268 cam, etc ,etc. 
I can vary my ignition advance from 0 to 48 degrees with the ECU.  I
guess i am wondering what it should be at cruise and full-throttle.  I
have heard that a big-block chevy should be able to take 40 degrees, but
that sounds high.  thanks!
-- 
Andy Quaas