I dont have a 340, but I have a tweaked-up 318....purple cam, ede intake, dougs headers, 650 ede carb, etc. Its in the same small block family so I'll chime in anyways with my random thoughts.
LOL
This is the perpetual pissing match that always seems to pop up. Truth is , there is NO answer guys.
Its all opinions....no factual "one is always better than another" answer, no matter what anyone tells ya. Someone who has owned only a big block or made the switch to one will say the BB is better. Someone who has owned only SB cars or has switch to SBs will say SB is best.
Asking this question is like asking what is better -- blond, brunette or redhead? Unless you can have all three at once, you have to pick one you like the best. There are SO many variables.
Truth is, we all think what we have is better than what someone else has for whatever reasons unless we are unhappy with it. Its how we validate our choices.
But lets get one thing said right up front.
No doubt, that if you have a big block at a car cruise or event, you get more "respect" than small blocks, right or wrong. And the folks with the big H, well, they are crowned kings as soon as the hood pops and people see those valve covers.
Right or wrong, that is what it is.
But the old "no replacement for displacement" is not exactly science either. More of a general statement, and it really only holds true in drag racing scenarios IMHO.
Clifford sells (sold?) products to increase the power for 6 bangers for years...their slogan was "6=8". And many people were very happy with their stuff. That company showed that displacement wasnt always king.
Current example - My wife's 2011 Mustang has a 3.7 v6 that will outrun previous year Mustang v8s (been there, done that....dont tell the wife). Her car would clean my fish's clock on a roadrace just from the benefit of the handling alone. And I would put it up against most cars on this forum. Its that impressive. And that is a STOCK v6.
Its all relative. Type of "race", conditions, driver, whats been done to the motor, how much weight the motor is dragging around, etc etc etc etc
And dont forget, you can get more displacement out of a small block without the added pounds of making the block bigger just by stroking it.
My 318 with all its goodies on it isnt the most powerful engine out there. But it gets around pretty good. People hear it and cant believe its "only a 318!?!?" Of course we all always want "more" dont we?. Aside from my wanting more low end off the line, its really way more than anyone needs for the street these days.
It has great power up top and revs high.
It does so good up high I am having a hard time considering a stroker smallblock to replace it. If it was running crappy it would be much easier to decide...LOL
But ok--back to e-bodies.
Yeah, the ebody is a heavy car. And having extra umph down low is good.
But the extra weight of a BB is more weight to move too....that affects mileage as well, if you care at all about that.
I get 10-12 mpg around town and 14-16 highway believe it or dont, and my foot is always in it. 3.55s out back, with a "heavy" 727 trans.
You need to decide what kind of "fun" you are looking for....some folks like to drive fast on the empty back roads and hug the corners and some like to drag race and go perfectly straight as fast as they can at the track.
No matter how stiff a torsion bar you throw at the ebody, the front end will always behave differently with a big block versus a small. Added weight means more weight to push around those corners, when the laws of physics kick in. And the downside to the stiffer suspension will be crummy comfort on average roads.
If you are drag racing and only worried about going straight and having the bragging rights to beating the other car by a tenth of a second, and dont care abot getting 2 gallons to the mile, maybe the big block is an advantage for sure. But I am not so sure that alone means the BB is "the only choice".
If you want to do nothing but torch your tires at every red light, low end is what you want. But how often do you want to shred the tires?
Can a big block car be modified to handle in the curves? Of course.
And a small block can be modified to put out 500 lb ft if torque.
Both cost $$$$.
But in the end, I think the only way to answer this question would be "choose whatever poison works best for you. "
Ok, I think I have stirred the pot long enough....LOL
Someone else's turn now...LOL