318 value

Because they come asking about a 318. Not a 360.
I agree as long the OP seems like he understands the general pro's and con's of building a 318 and not asking it to do something really beyond it's capabilities. Problem some people don't have really great understand hp, torque, rpm, powerbands, displacement, gearing and how it interconnects they don't realize their shooting themselves in the foot by some of their compromises.
Now if there's terminal damage to the 318 like a hole in the block, cracked cylinder or something else that would render their 318 unusable and they have to find another core to start with them MAYBE id consider a 360. But again as built 360s are pooches. Dished pistons, huge chambers in the heads, weeny cam... You'd have to put some flat tops in at least, maybe some head work and a cam at minimum to make THOSE run worth a shyt. So they might as well save the money they'd spend buying another engine and put that money they save by NOT buying that 360 into building a better 318. No worries about internal/external balance either, which is more money having to be spent on that 360....
I don't know about these reasons, but I understand why people push 360 (displacement) it generally makes more sense especially in a street car especially one the gonna run higher gears, low stall and operate in the lower rpm powerbands, but if the OP don't care then there's little reason for a 10 page argument for them to build something they don't even if it makes no sense to the average person.