318 to 340??

There’s no difference in size? If not that would be super easy and nice! Thanks
273 318 340 and 360 all pretty much the same size like said may have a different weighted balancer on the front or back and possibly the driver side l motor mount may need a little different set up for the 360 maybe, but I'm sure there others will chime in. it's not even worth thinking about if you got a 340 to put in there to replace a 318 any small thing you may have to do would be well worth it.