As they say in the US state of Maine "You can't get there from here."
You need to know the peach size before you cleaned an syrup'd them.
I checked USDA Table 8, it has nutrition, volume and weight information, and found:
Does anyone have a suggestion as to how many cups of peaches is equivalent to 8 peaches?
Based on the chart above, here is my guesstimate:
- the recipe is written for medium peaches (150 grams each) [medium is an assumption]
- 8 peaches times 150 grams = 1200 grams of peach needed
- 1200 grams of peaches / 154 grams for a measuring cup gives, just under 8 cups of peaches = 8 medium peaches
As you can see, there's allot of wiggle room in there. Consider keeping notes while cooking with goal of writing your own future recipe in grams.