I think, if a 318 guy actually took a 340 apart saw what's in it, they may change their mind. Mopar got it right with that engine, just the internals are enough to make you a believer. For example the forged crank, internally balanced, the heavy duty rods, the 68-71 pistons that are high compression, the heads with 2.02 valves, the 68 manual trans cam., the casting and port size...double roller timing chain, windage tray high flow exhaust manifolds I believe the main caps are unique to 340 , the 4 barrel intake and carb.. Prestolite Dual point distributor Not much to it but there is the "original" recipe.
I mean having rebuilt both more than one of each over the years its a no brainer. I will admit I've never rebuilt a 360.
I would be "unenthused" to take apart a 318,with a cast crank, the light duty rods, the flat top pistons, the small port heads with small ports and valves, the two barrel carb and intake, the nylon timing gear (I wonder how many out there still have that LOL!) then dick around with it, buy a cam, intake carb, what are you doing with the heads? replacing with Edelbrocks? that's $1500 there last I checked. then what .030 over with raised compression pistons? not cheap, cam?...lifters timing chain... headers. That 3 grand spent up quick I'm thinking...
P.S. I know that some early 318 I believe Truck engines had the forged crank and heavy duty rods, that would be a score to get that engine as a core IMO.