If BOTH slots are at full advance and the timing is still retarded
AND, the balancer is correctly calibrated to TDC, and the cam is correctly timed;
Then
I don't see any way past having to reclock the Reluctor.
There are at least three ways to do this;
1) machine a new slot in the reluctor, or
2) move the nylon drive gear
3) move the advance cam on the driveshaft.
#2 is by far the easiest
I had to do that on my last Slanty project. My advice is to have a spare gear on hand lol.