Are 340’s rare

I'll say it again, it's also about bore to stroke ratio.

My math says 4.04 minus 3.910 is .130 and not the .049 you calculated.

That's over an EIGHTH of an INCH bigger bore. That's a big thing.

I'll take RPM over stoke length any day.
That's because horsepower keeps climbing with RPM. That is, until parts are layin on the ground. lol