Will I regret change to 3.55s from 2.76s

First of all...don't over think it.
Second of all, if it ends up not suiting you, you can change it back.
By your posts, you like to accelerate from a stop briskly, and the 3:55s will put a smile on your face compared to the 2:76s.
And gas mileage isn't a huge deal to you anyway.
I say go for it and try it, what have you got to lose?
Maybe a little bit of time and a few bucks, but that's what it takes to enjoy our cars...

BTW, I have never worried about gas mileage on my old cars anyway, if it is decent, then that's a bonus!