Figuring out how much hop shot

Ingredients
1

Howdy, I have a recipe that calls for 3.5oz of 13.9% AA Columbus at 90 minutes. I would like to use hop extract to replace that addition. According to ProMash that works out to 198 IBU’s. I know that’s only theoretical, but anyone have a suggestion to figure out how much hop shot to use?

Also, as the hop shot is isomerized, it can be added at the end of the boil, just to sanitize, no?

The recipe I’m brewing the the Pliny clone from Zymurgy July 2010.

Thanks!

2

Maybe this will help:

http://www.northernbrewer.com/documentation/hopshot.pdf
3

Hop shot is not iso extract you have to boil to isomerize the alpha acids. If it was iso extract it would be complicated. As far as that is concerned you just replace the hops with the equiv amount of alpha with the hopshot.