Check your 318 crank and see if it's a forged one. If it is, use it. If you're not running over 400HP I wouldn't worry about a cast crank. The converter might be an issue if you need a particular high stall one for racing as it will have to be made. Having the crank drilled might be a better option so you have many more converters to choose from. If you're running a manual trans, the only issue is the pilot bearing. You would have to have a bushing made for the crank if it's the automatic version and not finished. Every one I've seen is drilled deep enough but some just didn't get the final machining for the bushing. The crank bolt pattern is the same for all V8's (except hemi) as far as I can remember.