Of course it had to go in from the top. I've heard they used a big hammer to masage one inner fender for fitment.
I've heard the Barracuda was the very first car to get a 340 too but Dart owners will argue that all day too.
There are no hammered fenderwells with a 383. 426 Hemi conversion by Hurst-Campbell on pass fenderwell but not the wedge. Even the 440 in M code 68's and 69 fit. You have to have the correct exhaust manifolds but they fit.