273 crank into a 340

I also have a void on that info. Good loco remembered it. Otherwise my answer would have looked like this.

The 273-318 and 340 have the same journal sizes. Weather or not the crank is forgded or cast, it will drop in.
MoPars cranks are tuff and will hold lots-o-HP.
All the fordged cranks to my knowleadge are from the same material, so the 273 crank is as tuff as the 340 crank.
Don't let the displacement fool you on how strong it is.

Now go back and re-read Loco's post. <LOL> I do believe they may be a cave eat to watch out for.
(I have a book around here somewhere......)