you can definatly just get a V8 k frame but that is usually more work and more expensive then a swap is. I havn't installed my schumacher swap yet so i can't tell you about how great they are but i can tell you it was a pleasure dealing with their company. They were very straight forward and answered all the questions i asked them.
Go to the schumacher home page and on the left find the section that says "73 and up A,B,F,M,J-body engine swap kits", click on that and you'll need the last one listed on that page for a 318. Hope that helps.
