To add to what Merlin said, the Lemans was built for Pontiac by Daewoo, so I don't think you will have any GM engine that will "bolt in".
The Sunfire turbo engine will most likely be hard to find, since they were only built a few years and built in (the engine) Brazil. This is not like putting a 3.1 V6 in a 4 cylinder Grand Am (which was offered in the Grand AM).
You will most likely have to remove the Daewoo engine, fit the Sunfire engine to the compartment, fabricate new mounts, check the fit or the drive axles into the stock knucles or use the entire transaxle from the Sunfire, check the length of the axles compared to the old ones, see if stock linkage works or fabricate new linkage mounts.
You will also have to use the Sunfire engine harness and marry that to the Lemans harness, use the Sunfire ECM.
Point is that while you may get all the hard parts within your budget, there will be a lot of labor and time involved and I would hate to tell you that it will work, only to find out that you may need to get new axles made because the originals are too short/long.
Some swaps are easier than others, unless you can find someone who has done it, you would be the first and would have to use the trial and error process to see if it will work.
Monday, October 20th, 2008 AT 8:04 AM