18x9 vs 18x11 - Rear wheels 72 Chevelle

[MBH]

I am trying to debate on which one to go with for my rear wheels on my chevelle. There is going to be a lot of power coming down, twin turbo ls 5.3, which makes me think the 11 inch would be best. However, I am not sure how much utility the extra size is going to get me. So I am here asking the pro's, thank you in advance.