Ken-

Do you think I should recheck the advance after I have tuned the secondaries?  I'm wondering if there might be a mixture change depending on when the secondaries open that may affect how fast the full timing can come in without detonation.  For that matter, should I tune the secondaries first?

 

Absolutely.  Once you do the timing first and then the secondaries, recheck the timing.  Both will affect each other to a point.  The secondaries will have less effect on timing than the other way around.  If there are large changes, do both again.  If there are tiny changes, you can stop there.