1999 Buick Regal Engine Replacment

The easy interchange you're looking for was common in the '60s and '70s, especially with Chrysler products and their parts between many different models. The problem today is there are major changes every year in the emissions systems and the Engine Computer that monitors it. Since you're familiar with the Hollander Guide, check the interchangeability of the camshafts and fuel injectors. I suspect you'll find they are different for different years and car models. Every time I read about someone switching to a different year or engine size, they always end up with mismatched connectors, poor performance, or a Check Engine light that won't stay off.

I myself put an '89 Dynasty engine into my '88 Grand Caravan. The entire job took seven hours and it has been running fine but for all these years the intake air temperature sensor has been laying on top of the engine because the newer engine didn't have the threaded port.

Other problems include exhaust manifolds not lining up with the exhaust pipes, differently-shaped oil pans, the fresh air tube and throttle body are different sizes, etc. The profile of the camshaft lobes sets the "personality" of the engine which will be different between car models. It affects emissions too.

To shift gears for a minute, overheating the engine doesn't necessarily mean the entire engine has to be replaced. That might be overkill. At worst the heads may be warped or cracked. Cracked ones, which aren't real common, must be replaced. Warped ones can be milled if the camshaft is in the block. For overhead cam engines, the heads must be heated and straightened, otherwise the cam journals will still be out of line. If you have the ability to replace an entire engine, you have the ability to replace the heads and gaskets. That would be easier and faster, and in the case of performance problems, you would eliminate all of the variables that come with the wrong engine.