I spoke with the tech people at Cloyes and the 9-3512X9 timing set I ordered from Summit will hopefully do the trick. The nine-position gear has a "+2" positon that is 1/4 the distance from 0 that the "+4" position is on my old gear.
On the Cloyes gear, that "+4" position that is on my old gear is actually stamped as "+8". He indicated that is how their gears are stamped: with the actual correction factor, so the final result will be two degrees not four.
Fingers crossed...waiting on the UPS guy now.