The engine in my 89 420sel which is not a daily driver needs more work, I think, than the car is worth. About 153k miles. If I use it almost entirely for easy highway driving, and could get a 300se engine with the same miles for about $450 tested; would that be terribly complicated and/or just a terrible idea. Somehow it just seems the sixes are generally simpler and last longer without overhaul. I'm not concerned with missing the v8 power as I have other v8 cars.