When you say stock bottom end ,,,,do you also mean compression ?
The 340 is one of the best engines ever,,,,,very strong from the factory .
But,,,it was still basically a warm stock factory engine .
Chrysler should have went to 11 to 1 compression or better .
And the heads needed a little bit better ports .
The X heads were very good in my opinion,,,,but why didn’t they step up to more advanced ports,,,,more in line with the W2 heads .
The 340 had a great foundation and many excellent parts .
Very good block ,,with excellent main caps .
Excellent forged steel crank .
Excellent forged rods with floating pins .
Double roller chain .
If they had the budget to do it ?
Added 11 to 1 pistons .
A nice Solid cam,,,range of .490” lift or more .
Solid adjustable valve train .
And a better flowing Aluminum intake .
With a nice sized Holley carb .
Chrysler had most of this stuff available,,,they even used a few better parts to beef it a little anyway .
However,,,,,the budgets were not that flexible back then,,,and they were primarily pushing the big blocks for power in those days .
The 340 could stand toe to toe with any other brand small block,,,,,and usually best them .
At least in factory form .
Tommy