Siv-- you are right, No Amarillo or Chinook in the boil on their website. I have brewed this a few times and did it both ways(with them in the boil and without). I thought it was closer to Flower Power when I added amarillo and chinook in the boil. The chinook @5 really added a nice aroma, and the early addition of Amarillo added some bitterness and flavor as well. As far as the IBU's-- again you are right about 75 according to Ithaca. I like it overly hopped, so I boosted up the hop amount, and it worked for me that way. I boil for 60 minutes, but when i took the brewery tour in Ithaca, they said they boil for 90 minutes. So if you add centennial @90 then you can probably reduce the amount of hops to achieve a higher IBU-- of course you would have to increase your preboil amount as well. Here is the second way I brewed a close clone of flower power that more resembles their recipe that you can try, but again I like the first one a bit more.
1.25oz Centennial@60, 1.0 Simcoe@30, 1.5 Cascade@10, 1.5Ahtanum@5---then dry hop 7 days 1.0oz each of simcoe, amarillo,chinook
This was 89.0 IBU's , I used 16lbs Briess 2-row, 1lb Honey malt, 0.5 Acidulated malt ----- aboout 7.5%abv
I liked this beer as well. And no, your not being a jerk at all, I like the feedback of different people--it makes us all better brewers.