advice for (potential) first time chopper builder?

hi. I have a friend of a friend who has a schwinn occ chopper he wants to motorize. I would most likely be building it. I have never done a chopper before, only beach cruisers. so I have some questions. I know that a mounting plate will be needed. are there any other special parts that are absolutely necessary for a chopper? also please explain why these parts are necessary, so I don't have to keep asking questions. also if any one person knows all the parts needed and the most economical way to aquire them, that would be great. also, if anyone knows if the mounting plate is compatible with the engines that have the larger 1.5 inch front motor mount, please let me know.