Any engine will fit any car, it's just a matter of how easily. It'll take a little more work than a Chevrolet engine but it should be just fine other than that. Not 100% on the compatibility of your other components though, you might need to swap some other stuff (flywheel, torque convertor, etc) ask a mechanic about that.
chev impala, chev Monte Carlo, Buick regal, Buick lesabre, and Pontiac Bonneville
Yes
For example: A very popular car in 1972 was the Chevrolet Monte Carlo. In 1973 the Monte Carlo, Buick Regal and the Oldsmobile Cutlass Suprime were sold very well. Their prices varied from $4,700US to $6,000US approximatly.
The 2002 Buick Regal has a V6 engine.
The 2003 Buick Regal has a V6 engine.
The 2004 Buick Regal has a V6 engine.
The 2001 Buick Regal has a V6 engine.
The 2011 Buick Regal has an inline 4 engine.
The 2012 Buick Regal has an inline 4 engine.
The 2013 Buick Regal has an inline 4 engine.
The 2014 Buick Regal has an inline 4 engine.
The 2004 Buick Regal has a 3.8 L base engine size.