I think the only thing I've ever driver that was slower than an Iron Duke F body was a 1986 S10 Blazer 4x4 with an Iron Duke, automatic, A/C and PS.
Needless to say, 0-60 was measured with a CALENDAR. 
Maybe, but i was getting about 27mpg with my 2.8 v-6, so it would not surprise me if the iron duke could get 30 or more with a 5sp manual; i think they were rated as 32mpg.
i should have never sold it.
2) The insurance companies go by VIN # when determining what is supposedly "high performance" or not.