I think the short 340 stroke is the reason why I have never been impressed by them.
If I want R's and longevity, I'll stick with my 318, if I want torque, I will go 360, or my favorite, 4" a 318..............
And also, in stockish form, I am not sure there is too much of a RPM-vs-Power output from the 340 to the 360. 3.31 with a heavier piston vs a 3.58 with a lighter piston, almost seems to balance out.
I have 302's with 1.88's on my 390. Makes wicked torque, but it is a truck engine, it never goes past 4800-5000. I would go big port if I was looking for that much power.