Go with a Chrysler 2.4 from a Stratus or P.T., the N/A version is very cheap and so are parts to build it. It's also almost the same motor as the 2.0 just bigger. You can use the same tranny (upgrade the clutch) and it will fit a lot better then a 2.7 or 3.0. Plus the after market for that motor is huge because of the SRT-4. You will get more H.P. cheaper with the 2.4 then the other two motors which have no after market.