340 or 408?

33IMP said
Turk, I think you and I are on opposite sides of the coin.
Engine masters did a comparison test of a 500hp sbc, and a 500hp bbc.
The 363" chevy rpm-ed like mad, cost about half again as much as the 454, needed better gas and much more gear.
The 454 made the same power, WAY more torque at street car levels, and would have been much more livable on the street, cheaper gas, better mileage, less freeway rpm. (and I believe if optimized, faster at the track)

True if those things matter to the OP or not, if streetability and rpm ain't a huge deal to you then the advantages of cid might not be a huge selling point, depends what the OP wants. But yes seem most generally would prefer the advantages of cid.

33IMP said
I suspect you would take the 363, with 4.56. I'd take the 454, with 3.55.

They should/could be putting similar torque to the ground.

The OP should have no shortage with torque even with 340 and 4.56.

say at 1.25 lbs-ft per cid

363 x 1.25 x 4.56 = 2069 lbs-ft
454 x 1.25 x 3.55 = 2015 lbs-ft