Did you check the timing marks, to make sure the damper hasn't slipped? I am questioning this, as I can't believe it would even crank over with that much initial timing, without kicking against the starter. Most N/A slants (key word "MOST") like a lot of initial advance (around 10-15*), and run best at less then 30* total. I will garuntee anything over 25* degrees on nitrous will break parts. My 66 Cuda 170 on nitrous runs between 15 and 20* fixed, depending on how big a shot. It has run a 12.905 at 101.65 mph at 3250 lbs.
Now that's impressive! The more I look at the 170, the more I think the little guy is the one to use as a foundation.
As for my car, the damper is indexed dead on at TDC, and has 2 degree notches beginning at 28 and ending at 36.
Yes, at 34 it wants to lightly kick back against the starter if I don't give it at least two healthy pumps before hitting the button.