Need drivetrain input on a 68 Dart project

I recently picked up a 68 Dart that I want to make into a GTS clone. The car was originally a 6-cyl car. I have three engines that I can choose from: 340, 440, or 331 Hemi. I plan on using a 727 tranny. Which engine I choose will be a matter of overall cost in regards to what will need to be changed in order to handle any of the engines, vs performance and resale value.

I would like to know what will need to be changed in order to handle each of the engines as far as other drivetrain components are concerned.