Dartfreak,
since your 318 is an '86 model, I'm willing to bet it's externally balanced, which means you can use the 360 trans and converter. Both are external balance, and both have the requisite weights necessary to mate up to your engine. As noted, however, you cannot interchange converters between transmissions (727 to 904).
On the driveshaft - I can't answer that question, but you can do a few quick measurements to verify.