I think you could reuse the bushing in the 340 if it's the large style one. I think that stuff has been the same for a long time. I know the bushing I bought was technically for a Dakota or Jeep or something like that from the 90's-2000's.
As for doing it again, in my specific case it's a bit of a "sorta". I have a really wacky build that I don't think anyone would want to duplicate because of how I got where I got. I would do it again, but I would do it a little differently. My swap started as a stock 5.7 with a carb and MSD ignition controller, then I swapped to a Megasquirt fuel injection setup with an aftermarket intake (still with the MSD ignition), then I swapped a cam, then I redid the whole wire harness to better integrate the new wires. If I were to do it again I would try to really plan everything out better and do it all at once a little more cleanly. Admittedly my swap was somewhat intentionally done in steps because I wanted to keep driving the car. If I would have waited until everything fell together it would have been years before I would have been able to enjoy the car.
Long story short, the main reason I did the swap was because of the potential the newer engines have. I looked into stroker small blocks, supercharged small blocks, aluminum big blocks, and the new Hemis. They all were coming in with similar bottom line prices and the Hemi was the first thing I found a deal on. For me, half the fun is the project itself. Figuring out how to make it work is frustrating from time to time, but also rewarding. My car is one of a kind as far as I'm concerned, and that's part of the fun.