I would start here, and then read the related articles on the site:
Upgrading Older Road Bicycles
A complete answer would require a list of the components on the "donor," which you might be able to find somewhere on the www. If you find one, then you can start taking measurements of your existing bike and start looking to see what will transfer and what won't.
Alternatively, perhaps you should just buy the donor, figure out what will transfer and what won't. This may be the best course of action if you can't find reliable specs on the donor before buying it. Before you start taking anything apart, make a list of what additional parts will need to be acquired and add up the total cost. Then decide if you want to proceed or just resell the donor, hopefully making back whatever you paid for it.