Should I bore a 74 318 to 340 ci or just go with a 360?

The 340 has a reputation because it's the only small block performance engine Mopar built during the horsepower era. You can build a 318 just the same. If you bore your 318 to 340 it's still a 318. It says so right there on the block. The only reason to have a 340 in the first place is the cool factor. I made a decision a long time ago to leave the 340s to the people that think they need a 340. The decision came when I cracked a cylinder wall in my 340. You find out real quick that you can't go to Wal Mart and buy a new block on the cheap like you can a 360 or a 318. It's hard enough being a Mopar guy in the first place. If I was about parts availability and budget I would run a Chevy. But let's not add any more trouble than we already have.
Here's the deal. Two people with two different engines are given the same budget. One has a 318 and the other has a 340. After the build is complete they'll have engines that run pretty close to neck and neck at the finish line. Ask anyone with a 340 if they've ever lost to a 318 at the track. Happens all the time.