4-Speed from a 340 to a 318 pilot bushing question

I wrote a post last fall about selling my 1970 340 Dart Swinger without the 340 (non-matching) that is in it. I plan on putting the 340 in my 71 Duster which currently has a 318. I had wanted to do that before last winter set in but wasn't able to get it done so I am now going to finally try to get it done. I am going to pull the 340 soon and either sell the Swinger as a roller or sell it with the 318 from the Duster. My question is, being the Swinger is a 4-speed and the the Duster is an automatic, will the 4-speed bolt up to the 318 as-is or am I going to have to install a pilot bushing in it? In other words, what is the likelihood the 318 would already be drilled for a pilot bushing for a 4-speed? If it isn't, will I have to use a special bushing?