I think a wideband is the way to go. A little fatter rod on the little end. Doesn't sound like it's that far off. As long as it doesn't ping. Have you noticed a difference in how it runs or sounds?
I just got my valvetrain sorted and checked my vacuum. I have 12" hot in park and 10" in drive. Will probably change the rods first without a spring change and go from there.
