Increased rocker arm ratio doesn't increase overlap by any appreciable amount. A common point of reference with over lap is at .050". Multiply .050" times the common rocker ratios and see what you get. -12* overlap might become -10*. Going from 1.55 to 1.75 gives theoretical gain of .010" lift @ .050"
I was hoping you'd chime in Dave. I lost your numbers months ago and Vonage search doesn't work like it did in the old days. i.E. doesn't work at all. lol