Dizzy curve

Hey guys i got a question stock 225 with 3.23 gears in a 1965 valiant wagon im working on the dizzy curve. i know the heavier wagon will effect the curve and spring type. my question is with the heavier wagon i would want a slower curve correct? im all in at 2800rpm and she pings not too much, if i retard the timing the car starts like **** so im guess the curve is coming in too soon?