yeah, I'd go along with that. But I've personally seen variances greater than 30% from one chassis dyno to the next which easily account for it.
I went to the QLD Z Car Club dyno day just last Saturday. There was a full house 3.1 there as well, which was the favourite at the start of the day. He was only beaten by 2 cars with 2850cc engines both built by a mate of mine.
On a side note, my 1200 (L18 1995cc) had 32% less power than the my mate's 240Z that won the dyno day
but I still beat him around the racetrack