I'm looking at hardware to mount my new lift off hood and I see these type of fasteners come in different lengths. What dictates which length one you need

I ordered a kit of ten Dzuz fasteners and Moroso mounting plates for .500 depth, they worked on the four fronts and the two in the back (I also used the stock hinges on the rear corners, I didn't want a lift off hood anymore) without any notching, the two on each side required notching the sides of the fibreglas hood, no big deal. As far as the .150 differences in depth on the .500 versus the .650, it wouldn't have made enough difference on the sides to make it worthwhile to switch to the .650 Dzuz fasteners and plates. your situation mad ebe different than mine, I would look closely before deciding on which type or types to use, look twice, buy once You may need more than one depth and style