I have what I think is a 76 318 block.....eddie performer nmanifold, eddie 1406 carb (was a 1407 when I got it), j heads, headers, some purple cam in it.....I was told the engine was rebuilt stock at some point but then got some contradictory info from someone else who said the engine is an unknown....I have checked compression and listed it here, and according to folks who read it then I have a standard compression engine.
I put a 2400 stall behind it with the 727.
The car runs 2.76 gears. So its not a tire -scorcher off the line.
"No, its not a hemi or a big block or a 340......".....and yeah sometimes I can see the "disappointment" in the eyes of the giddy car show attendee who asks "What engine is it?!!?". Cant say I care all that much.
When this engine revs up it screams....have had it to about 6500 rpm and it still pulls hard....afraid to break something any higher.....I am convinced that with 3.55s it will really come alive.....but even as-is, I have put a few "tough guys" in wanna-be racers to shame......
If you really just want a nice looking cruiser that has some pep, I say go with the 318.
If you want the bragging rights to say "It has a 340" or "it has a big block", go for it.
Someone painted my 318 orange before I got it, so half the people who look at it think its a 340 anyways.,...LOL
Just think about what you intend to do with the car and then decide.
On one hand I wouldnt mind being able to say I have a hemi in mine versus a 318....but my car is fun to drive , is reliable and and gets no worse mileage than my dakota or durango, both with small blocks.
If I were in your shoes, I would tweak up the 318 to play with it a while since you have the parts (right?)...and then on the side work on the 340 if you have it already or something else.