Oh dear God! 318 stroker

By the time you get done cobbeling together a cut down 360 crank, paid for the crank maching and custom pistons, redoing stock rods, and balancing the mess, you WILL be sorry you didn't just get the 390 kit and an extra 50 inches MORE than an ordinary 340.
That's kinda like stroking a 383 to 426 (only!). Why bother?