well now really you dont need to do a complete swap. you can just swap the heads and some pieces here and there and the pcm. the wiring is the same. the only difference in the bottom end is the pistons. i know of guys just doing the head swap, pcm, timing and just leave the sohc pistons in. you loose a little compression that way but its probably the cheapest way to go. now as of places online the only i know of is
http://www.6thplanetusedparts.com/ . now some people have had issues with them but they back up everything they sell so i dont see what would be wrong. also if you have any more questions about the swap and what would be best you can just ask them if you feel like something is missing or if you what to know if the complete engine swap would be better then the head swap. i dont know exactly what they would say, id say the head swap would be easier yet the piston thing is the only downside but nothing bad. now they might be a little more expensive too then hitting up a junkyard. now if your also looking for new parts online check out
www.saturnparts.net or
www.saturnparts.com . now for remanufactured you will probably just have to do a search, but i know jasper engines are really good replacement engines with 3 year 75,000 mile warranty. but i think it might be better to go used since you still have to get a pcm and if you do just the head swap then a timing set and i do believe everything else is fine.