hops addition suggestions?

I am brewing an IIPA using 16.5lb pilsner and 1.7 lbs victory target og of 1.083 for 6 gal batch. I have 2 oz Cascade at 7.8AA , 1 oz Summit at 14AA and 0.5oz admiral at 13.5AA. I plan on dry hopping with an oz each of summit and cascade. I've been reading all this stuff about late hop additions but I'm worried about getting enough IBU for this big a beer. I think a lot of people add high alphas first as bittering but this may not be as applicable anymore with such high quality hops available that high alpha hops now seem to have much smoother bitterness for all that aroma and flavor. any suggestions on what to add when would be appreciated. may even consider "continuous" hopping as in DFH 90 min.

If you are set on dry hopping with 1oz each of summit and cascade, I don't think you can meet IIPA style IBUs with what you have left. However, styles be damned, FWH'n the remainder should get you to a balanced enough bitterness and a pretty good end product.

Are you boiling for 90min? If so, you will get better extraction and that will help.

yes, I've actually already brewed this batch. ended up with a little much too much wort out of the mash tun so the boil ended being 105 minutes. first hop addition (1 oz) cascade at 40 min, then 0.5 oz cascade 0.5 oz summit at 60 min, another 0.25 oz summit 0.25 oz cascade and 0.25 oz admiral at 80 min and the remaining addition (same as last) at 100min. the admiral smelled so delicious I wanted it to make up a large portion of the aroma. the airlock is bubbling away and it smells superb. will let you know how it turns out. probably not for another month or two since it started at 1.087.