Guy i have always trusted/ respected a ton, Ken Hensley, Hensley performance, built me a 416 stroker shortblock long time ago... probably better than 20 years ago now.
I remember asking him if you had say a 340/360 and swapped heads, cam etc over to a stroker, how much is it worth at the track. He told me, all things being the same, 3 or 4 tenths. Never forgot that.
Regards the OP, and his large gain, besides the extra cubes, the BIG thing that jumps out is going from stock eddies to Trick Flows. Just a guess, but i wouldn't be the least surprised If there was 60 horse difference between just the two sets of heads, msybe a bit more. That and the inches is a lot
